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Wyświetlanie 1-76 z 76
Tytuł:
Theoretical Studies of the Local Structures and EPR Spectra for $VO^{2+}$ in $MB_4O_7$ (M = Zn, Cd) Glasses
Autorzy:
Li, C.
Zheng, X.
Powiązania:
https://bibliotekanauki.pl/articles/1206562.pdf
Data publikacji:
2014-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.Fc
Opis:
Electron spin resonance spectral parameters (g factors $g_{∥}$, $g_{⊥}$ and hyperfine structure constants $A_{∥}$, $A_{⊥}$) of a tetragonal $V^{4+}$ centers in $MB_4O_7$ (M = Zn, Cd) are theoretically investigated by using the perturbation formulae for a $3 d^1$ ion in tetragonally compressed octahedra. In these formulae, the contributions to the g factors from the tetragonal distortion, characterized by the tetragonal field parameters $D_{s}$ and $D_{t}$ are taken into account by considering the local structures of the ligand octahedron around the $V^{4+}$ due to the Jahn-Teller effect. Based on the calculations, the ligand octahedra around $V^{4+}$ are suggested to suffer about 5.7% and 4.3% relative compression along $C_4$ axis for $MB_4O_7$ glasses with M = Zn and Cd, respectively, and negative signs of the hyperfine structure constants $A_{∥}$ and $A_{⊥}$ for $V^{4+}$ centers in $MB_4O_7$ glasses were suggested in the discussion.
Źródło:
Acta Physica Polonica A; 2014, 125, 1; 73-76
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Theoretical Studies of the Spin Hamiltonian Parameters and Local Structures for the Two Tetragonal $Cu^{2+}$ Centers in $Ca(OH)_2$
Autorzy:
Zhang, H.
Wu, S.
Zhang, Z.
Powiązania:
https://bibliotekanauki.pl/articles/1493658.pdf
Data publikacji:
2011-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.Fc
Opis:
The spin Hamiltonian parameters (g factors $g_{∥ },$ $g_{⊥}$ and the hyperfine structure constants $A_{∥ },$ $A_{⊥}$) and the local structures for the two tetragonal $Cu^{2+}$ centers I and II in $Ca(OH)_2$ are theoretically studied from the perturbation formulae of these parameters for a $3d^9$ ion under tetragonally elongated octahedra. The $[Cu(OH)_6]^{4-}$ clusters on the substitutional $Ca^{2+}$ site are found to suffer the relative elongations by about 0.083 Å and 0.065 Å for centers I and II, respectively, along the $C_4$ axis due to the Jahn-Teller effect. The above tetragonal elongations may entirely depress the original trigonal distortion of the host $Ca^{2+}$ site in $Ca(OH)_2$. The calculated spin Hamiltonian parameters based on the above Jahn-Teller elongations show good agreement with the experimental results. The EPR spectra and the local structures for the two centers are compared with one another.
Źródło:
Acta Physica Polonica A; 2011, 120, 3; 507-511
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetization Relaxation in CdMnS
Autorzy:
Witowski, A. M.
Kutter, Ch.
Mac, W.
Wyder, P.
Powiązania:
https://bibliotekanauki.pl/articles/1929759.pdf
Data publikacji:
1993-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.Fc
Opis:
The static magnetization measurements and relaxation of magnetization data for two Cd$\text{}_{1-x}$Mn$\text{}_{x}$S samples with different composition are presented. The magnetization is described by the modified Brillouin function. The magnetization relaxation shows unusual composition dependence. This behavior is explained by cross-relaxation to the unknown fast relaxing centers introduced during growth.
Źródło:
Acta Physica Polonica A; 1993, 84, 4; 798-800
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
EPR of Vanadyl Ion Impurities in Single Crystals of RbHC$\text{}_{2}$O$\text{}_{4}$
Autorzy:
Singh, V.
Jain, V. K.
Powiązania:
https://bibliotekanauki.pl/articles/2035648.pdf
Data publikacji:
2002-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.Fc
Opis:
The EPR of VO$\text{}^{2+}$ in RbHC$\text{}_{2}$O$\text{}_{4}$ single crystals has been studied in X-band at≈290 K. Three sites have been observed. VO$\text{}^{2+}$ enters the lattice at substitutional and interstitial sites. Spin-Hamiltonian parameters are evaluated.
Źródło:
Acta Physica Polonica A; 2002, 102, 6; 795-799
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetization Relaxation in a Four-Level System
Autorzy:
Witowski, A. M.
Powiązania:
https://bibliotekanauki.pl/articles/1929757.pdf
Data publikacji:
1993-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.Fc
Opis:
The relaxation of magnetization in a four-level system (e.g. Co$\text{}^{2+}$ in II-VI compounds) is discussed. It is shown that in the heat pulse experiment the slowest relaxation time is basically observed.
Źródło:
Acta Physica Polonica A; 1993, 84, 4; 795-797
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electron Paramagnetic Resonance and Superposition Model Analysis of Zero Field Splitting for Mn$\text{}^{2+}$ in Double Nitrates
Autorzy:
Jain, V. K.
Prakash, V.
Powiązania:
https://bibliotekanauki.pl/articles/1929829.pdf
Data publikacji:
1993-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.Fc
Opis:
Electron paramagnetic resonance of Mn$\text{}^{2+}$ in La$\text{}_{2}$Zn$\text{}_{3}$(NO$\text{}_{3}$)$\text{}_{12}$ • 24H$\text{}_{2}$O single crystals is studied at ≈ 9.45 GHz. Mn$\text{}^{2+}$ substitutes for Zn$\text{}^{2+}$ sites. The spin-Hamiltonian parameters are evaluated at 290 K. The superposition model has been applied to the zero-field splitting parameter D for Mn$\text{}^{2+}$ in Ce$\text{}_{2}$Mg$\text{}_{3}$(NO$\text{}_{3}$)$\text{}_{12}$ • 24H$\text{}_{2}$O and La$\text{}_{2}$Mg$\text{}_{3}$ (NO$\text{}_{3}$)$\text{}_{12}$ • 24D$\text{}_{2}$O at both sites. It is shown that the calculated values of D are in agreement with the experimental values if local relaxation effects are taken into account.
Źródło:
Acta Physica Polonica A; 1993, 84, 6; 1111-1115
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electron Paramagnetic Resonance of Cr$\text{}^{3+}$ in Rb$\text{}_{x}$(NH$\text{}_{4}$)$\text{}_{1-x}$Al(SO$\text{}_{4}$)$\text{}_{2}$·12H$\text{}_{2}$O
Autorzy:
Takhur, S.
Jain, V. K.
Powiązania:
https://bibliotekanauki.pl/articles/1931369.pdf
Data publikacji:
1994-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.Fc
Opis:
The EPR of Cr$\text{}^{3+}$ in mixed alum Rb$\text{}_{x}$(NH$\text{}_{4}$)$\text{}_{1-x}$Al(SO$\text{}_{4}$)$\text{}_{2}$·12H$\text{}_{2}$O has been studied at ca. 300 K and ca. 9.45 GHz. The EPR spectrum for x between 30 to 70% shows more than one kind of chromium complexes. The variation in magnitude of zero-field splitting parameter D indicates that the monovalent ions probably play an important role in the trigonal distortion of the water octahedron around the trivalent metal ion in alums.
Źródło:
Acta Physica Polonica A; 1994, 85, 6; 985-988
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical Studies of Magnetization Relaxation of Mn$\text{}^{2+}$ in Zinc Blende Crystals
Autorzy:
Witowski, A. M.
Powiązania:
https://bibliotekanauki.pl/articles/1924219.pdf
Data publikacji:
1992-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.Fc
Opis:
The results of numerical simulation of magnetization relaxation of Mn$\text{}^{2+}$ centers are presented. They show that the relaxation can be exponential in certain time intervals, with the relaxation rate related by a simple formula to the transition probabilities.
Źródło:
Acta Physica Polonica A; 1992, 82, 5; 876-878
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electron Paramagnetic Resonance of Mn$\text{}^{2+}$ and Cu$\text{}^{2+}$ in Cs$\text{}_{2}$C$\text{}_{2}$O$\text{}_{4}$·H$\text{}_{2}$O Single Crystals
Autorzy:
Jain, V. K.
Kapoor, V.
Powiązania:
https://bibliotekanauki.pl/articles/1920671.pdf
Data publikacji:
1992-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.Fc
Opis:
The electron paramagnetic resonance spectra of Mn$\text{}^{2+}$ and Cu$\text{}^{2+}$ in Cs$\text{}_{2}$C$\text{}_{2}$O$\text{}_{4}$·H$\text{}_{2}$O single crystals are studied at ~9.45 GHz and 290 K. The spectra at 77 K show no appreciable change. The ions appear to enter the lattice at interstitial sites. The spin-Hamiltonian parameters are evaluated at 290 K.
Źródło:
Acta Physica Polonica A; 1992, 81, 4-5; 579-582
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electron Paramagnetic Resonance of Mn$\text{}^{2+}$ in Tl$\text{}_{2}$Mg(SeO$\text{}_{4}$)$\text{}_{2}$·6H$\text{}_{2}$O Single Crystals
Autorzy:
Anju,
Jain, V. K.
Powiązania:
https://bibliotekanauki.pl/articles/1920804.pdf
Data publikacji:
1992-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.Fc
Opis:
The electron paramagnetic resonance of Mn$\text{}^{2+}$ in Tl$\text{}_{2}$Mg(SeO$\text{}_{4}$)$\text{}_{2}$·6H$\text{}_{2}$O single crystals has been observed at 298 K and 77 K at ~9.45 GHz. Mn$\text{}^{2+}$ has been found to substitute for Mg$\text{}^{2+}$ exhibiting two magnetically inequivalent complexes. The electron paramagnetic resonance spectra have been analysed using the spin Hamiltonian appropriate for rhombic symmetry.
Źródło:
Acta Physica Polonica A; 1992, 81, 6; 699-702
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Zero-Field Splitting Parameters of $Cr^{3+}$ in Lithium Potassium Sulphate at Orthorhombic Symmetry Site
Autorzy:
Pandey, S.
Kripal, R.
Powiązania:
https://bibliotekanauki.pl/articles/1400393.pdf
Data publikacji:
2013-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.-v
76.30.Fc
Opis:
The superposition model is used to investigate the crystal field parameters, $B_{kq}$ of $Cr^{3+}$ in lithium potassium sulphate. The zero field splitting parameters D and E are then determined using microscopic spin Hamiltonian theory and compared with the experimental values obtained by electron paramagnetic resonance. Both zero field splitting parameters D and E evaluated theoretically are in good agreement with the experimental values. The results suggest that the $Cr^{3+}$ ion occupies substitutional K^{+} site in lithium potassium sulphate.
Źródło:
Acta Physica Polonica A; 2013, 123, 1; 101-105
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
EPR in Kagome Staircase Compound Mg$\text{}_{2.997}$Co$\text{}_{0.003}$V$\text{}_{2}$O$\text{}_{8}$
Autorzy:
Aleshkevych, P.
Fink-Finowicki, J.
Powiązania:
https://bibliotekanauki.pl/articles/2047230.pdf
Data publikacji:
2007-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.Da
76.30.Fc
Opis:
The paramagnetic resonance of Co$\text{}^{2+}$ ions in Mg$\text{}_{2.997}$Co$\text{}_{0.003}$V$\text{}_{2}$O$\text{}_{8}$ single crystals are reported. The EPR spectrum shows two groups of resonance lines associated with two crystallographically nonequivalent Co ions positions that are known in the kagome staircase system as "cross-tie" and "spine" sites. No preferential occupation of Co$\text{}^{2+}$ ions in the kagome lattice was observed. The ground state was described by spin-Hamiltonian with an effective electronic spin S=1/2 and nuclear spin I=7/2. The local symmetry of oxygen octahedron surrounding Co ions, main values of the g-factors, and hyperfine structure were determined for both cobalt positions.
Źródło:
Acta Physica Polonica A; 2007, 111, 1; 105-110
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
EPR Discovery of a New Pressure-Induced Low-Spin Phase in (2Me-5Et-PyH)[Fe(Th-5Cl-Sa)$\text{}_{2}$]
Autorzy:
Krupska, A.
Augustyniak-Jabłokow, M. A.
Yablokov, Yu. V.
Zelentsov, V. V.
Ulanov, V. A.
Mroziński, J.
Powiązania:
https://bibliotekanauki.pl/articles/2046891.pdf
Data publikacji:
2006-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.Fc
75.30.Wx
Opis:
Electron paramagnetic resonance studies of the high-spin (HS) ↔ low-spin (LS) transition in 2-methyl-5-ethyl-pyridine-5-chloro-salicylalt hiosemicarbazonatoferrate(III) performed under hydrostatic pressure up to 500 MPa in a temperature range of 80-310 K have revealed two modifications of the low spin complexes: low-pressure (LS1) and high-pressure (LS2) ones. Under atmospheric pressure LS1 appears on cooling and disappears on heating at 220 K. The hydrostatic pressure shifts the transition to higher temperatures. Below 275 K an increase in pressure to 410 MPa results in abrupt changes in the g-factor and widthΔ B of the EPR line indicating a transition to a new phase. The pressure-induced transition LS1 ↔ LS2 is almost independent of T up to 275 K, where at a pressure of 420 MPa a triple point is observed. The LS1↔ LS2 and HS↔ LS2 (at T>260 K) transitions occur with a large hysteresis of about 95 MPa. The process of the spin transition has been shown to begin with the formation of domains of LS complexes in the matrix of HS ones. The response of the domains to external factors has been studied.
Źródło:
Acta Physica Polonica A; 2006, 110, 1; 81-95
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Theoretical Analysis of Zero Field Splitting of $Mn^{2+}$ in Ammonium Oxalate Monohydrate
Autorzy:
Kripal, R.
Pandey, S.
Powiązania:
https://bibliotekanauki.pl/articles/1535738.pdf
Data publikacji:
2010-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.70.Ch
76.30.Fc
Opis:
The superposition model has been used to investigate the substitution of $Mn^{2+}$ in ammonium oxalate monohydrate. The zero field splitting parameters D and E calculated by the superposition model are compared with the experimental values $D_{exp}$ and $E_{exp}$, respectively, for $Mn^{2+}$ obtained by electron paramagnetic resonance. Both the zero field splitting parameters D and E calculated theoretically are in good agreement with the experimental values $D_{exp}$ and $E_{exp}$. The result indicates that the $Mn^{2+}$ ion substitutes for the $NH_4^{+}$ ion in ammonium oxalate monohydrate.
Źródło:
Acta Physica Polonica A; 2010, 118, 4; 629-632
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Theoretical Studies on the Local Structure and Spin Hamiltonian Parameters for Single Cu²⁺ Ion in BaF₂
Autorzy:
Lin, J.
Xiao, P.
Zhao, Y.
Zhang, B.
Yang, Y.
Powiązania:
https://bibliotekanauki.pl/articles/1398965.pdf
Data publikacji:
2016-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Dg
76.30.Fc
Opis:
The spin Hamiltonian parameters (g-factors and the hyperfine structure constants) and local structure are theoretically studied for single Cu²⁺ ion in BaF₂ from the high-order perturbation formulae of these parameters for 3d⁹ ions in tetragonally elongated octahedra. In the calculations, the ligand orbital and spin-orbit coupling of the impurity Cu²⁺ are taken into account, based on the cluster approach. Due to the Jahn-Teller effect and size mismatching substitution, the impurity Cu²⁺ is found to be located at a distance of about 0.2 Å from the nearest fluorine plane. The signs of the hyperfine structure constants $A_∥ $ and $ A_⊥ $ are suggested. The theoretical spin Hamiltonian parameters based on the above local structure are in good agreement with the observed values.
Źródło:
Acta Physica Polonica A; 2016, 129, 6; 1173-1177
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Impact of Exchange-Correlations Effects (+U Corrections) on the Energy Levels of Mn and Fe Impurities in GaN and AlN: A Comparison with Experiment
Autorzy:
Zakrzewski, T.
Bogusławski, P.
Powiązania:
https://bibliotekanauki.pl/articles/1399156.pdf
Data publikacji:
2013-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Pp
76.30.Fc
Opis:
Electronic structure of Mn and Fe impurities in GaN and AlN are calculated within the density functional theory in the generalized gradient approximation without and with the +U corrections. The comparison with the available experimental data shows that the results obtained with U = 0 are in good agreement with experiment. Inclusion of +U corrections makes the agreement worse.
Źródło:
Acta Physica Polonica A; 2013, 124, 5; 898-900
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
EPR Study of the Two-Dimensional Quantum System $Cu(en)(H_2O)_2SO_4$
Autorzy:
Tarasenko, R.
Orendáčová, A.
Čižmár, E.
Orendáč, M.
Zvyagin, S.
Wosnitza, J.
Powiązania:
https://bibliotekanauki.pl/articles/1427109.pdf
Data publikacji:
2012-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.Fc
75.40.-s
Opis:
The angular dependence of electron paramagnetic resonance spectra of $Cu(en)(H_2O)_2SO_4$ single crystals was studied in the X-band frequency range at temperatures 4 and 300 K. Analysis of the linewidth at 300 K revealed nice agreement with the angular variation of the g-factor. This coincidence is the manifestation of the symmetric and antisymmetric exchange coupling, as main broadening mechanisms in $Cu(en)(H_2O)_2SO_4$ at high temperatures. The radical change of the angular dependence of the linewidth observed at 4 K can be ascribed to dipolar coupling.
Źródło:
Acta Physica Polonica A; 2012, 121, 5-6; 1095-1097
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Intramolecular and Lattice Dynamics in V$\text{}_{6-n}^{IV}$V$\text{}_{n}\text{}^{V}$ O$\text{}_{7}$(OCH$\text{}_{3}$)$\text{}_{12}$ Crystal
Autorzy:
Yablokov, Yu. V.
Augustyniak-Jabłokow, M. A.
Borshch, S.
Daniel, C.
Hartl, H.
Powiązania:
https://bibliotekanauki.pl/articles/2043556.pdf
Data publikacji:
2005-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.Fc
36.40.Cg
Opis:
Multi-nuclear mixed-valence clusters V$\text{}_{4}^{IV}$V$\text{}_{2}^{V}$O$\text{}_{7}$(OCH$\text{}_{3}$)$\text{}_{12}$ were studied by X-band EPR in the temperature range 4.2-300 K. An isotropic exchange interactions between four V$\text{}^{IV}$ ions with individual spin S$\text{}_{i}$=1/2 determine the energy levels structure of the compound with the total spin states S=0, 1, and 2, which are doubled and split due to the extra electron transfer. The spin-Hamiltonian approach was used for the analysis of the temperature dependences of the EPR spectra parameters and the cluster dynamics. Two types of the electron transfer are assumed: the single jump transfer leading to the splitting of the total spin states by intervals comparable in magnitude with the exchange parameter J≈100-150 cm$\text{}^{-1}$ and the double jump one resulting in dynamics. The dependence of the transition ratesν$\text{}_{tr}$ on the energy of the total spin states was observed. In particular, in the range 300-220 K theν$\text{}_{tr}$ ≈0.7×10$\text{}^{10}$ cm$\text{}^{-1}$ and below 180 K the ν$\text{}_{tr}$≈1×10$\text{}^{10}$ cm$\text{}^{-1}$ was estimated. The g-factors of the spin states were shown to depend on the values of the intermediate spins. A phase transition in the T-range 210-180 K leading to the change in the initial V$\text{}^{IV}$ ions localization was discovered.
Źródło:
Acta Physica Polonica A; 2005, 108, 2; 271-281
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigations on the EPR Parameters of $KMgF_3$:$Cr^{+}$
Autorzy:
Kuang, M.
Wu, S.
Hu, X.
Li, G.
Zu, H.
Powiązania:
https://bibliotekanauki.pl/articles/1365348.pdf
Data publikacji:
2014-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Dg
76.30.Fc
Opis:
The electron paramagnetic resonance parameters (i.e., g factor, hyperfine structure constant and superhyperfine parameters) of $KMgF_3$:$Cr^{+}$ are theoretically investigated from the perturbation formulae of these parameters for an octahedral $3 d^5$ cluster. As for the calculations of g factor and hyperfine structure constant, both the contributions from the crystal-field and charge transfer mechanisms are included based on the cluster approach. The metal to ligand charge transfer contribution to the g-shift Δg ( ≈ g-2.0023) is the same (negative) in sign and much larger in magnitude as compared to the crystal-field one. The conventional argument that the charge transfer contributions to zero-field splittings are negligible for $3 d^5$ ions in fluorides is no longer suitable for Δg analysis of $KMgF_3$:$Cr^{+}$ due to the dominant second-order charge transfer perturbation term. The charge transfer contribution to hyperfine structure constant exhibits the same sign and about 4% of the crystal-field one. The unpaired spin densities of the fluorine 2s, 2pσ and 2pπ orbitals are quantitatively acquired from the relationships with the relevant molecular orbital coefficients using the uniform model. The present treatments are superior to the previous calculations of directly fitting the experimental superhyperfine parameters.
Źródło:
Acta Physica Polonica A; 2014, 125, 5; 1224-1228
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
EPR Spectroscopy of the Mn^{2+} and Cu^{2+} Centres in Lithium and Potassium-Lithium Tetraborate Glasses
Autorzy:
Padlyak, B.
Wojtowicz, W.
Adamiv, V.
Burak, Ya.
Teslyuk, I.
Powiązania:
https://bibliotekanauki.pl/articles/1550290.pdf
Data publikacji:
2010-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.Fc
81.05.Kf
Opis:
The electron paramagnetic resonance spectra of the glasses with $Li_{2}B_{4}O_{7}$ and $KLiB_{4}O_{7}$ compositions doped with Mn and Cu were investigated. On the basis of obtained EPR spectra analysis it was shown that the Mn and Cu impurities are incorporated into the glass network as $Mn^{2+} (\text{}^{6}S_{5//2}, 3d^{5})$ and $Cu^{2+} (\text{}^{2}D_{5//2}, 3d^{9})$ ions. The $Mn^{2+}$ EPR spectra in the glasses with $Li_{2}B_{4}O_{7}$ and $KLiB_{4}O_{7}$ compositions are characterised by the following parameters, measured at T = 300 K: isotropic g-factor ($g_\text{iso}$ = 2.00 ± 0.05), isotropic hyperfine constant ($A_\text{iso}$ = (8.65 ± 0.05) mT) and peak-to-peak linewidth of hyperfine components $ΔB_{pp}$ = (3.50 ± 0.05) mT. The $Cu^{2+}$ EPR spectra in the glasses with $Li_{2}B_{4}O_{7}$ and $KLiB_{4}O_{7}$ compositions, registered at T = 300 K are characterised by the same g-values ($g_∥$ = 2.34 ± 0.05, $g_⊥$ = 2.06 ± 0.05) and peak-to-peak line width of hyperfine components ($ΔB_{pp}^{∥}$ = (5.11 ± 0.05) mT, $ΔB_{pp}^{⊥}$ = (1.80 ± 0.05) mT), whereas anisotropic hyperfine constants show some differences ($A_{∥}$ = (14.28 ± 0.05) mT, $A_{⊥}$ = (2.34 ± 0.05) mT for glass with $Li_{2}B_{4}O_{7}$ composition and $A_{∥}$ = (14.21 ± 0.05) mT, $A_{⊥}$ = (2.55 ± 0.05) mT for glass with $KLiB_{4}O_{7}$ composition). The possible local structure of the $Mn^{2+}$ and $Cu^{2+}$ centres in the lithium and potassium-lithium tetraborate glass network has been considered.
Źródło:
Acta Physica Polonica A; 2010, 117, 1; 122-125
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Really First Principles Calculations for CoF₃
Autorzy:
Radwanski, R.
Nalecz, D.
Krupska, M.
Piwowarczyk, T.
Ropka, Z.
Powiązania:
https://bibliotekanauki.pl/articles/1385724.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.Fc
75.10.Dg
Opis:
We have derived the low-energy electronic structure of CoF₃, originating from the strongly-correlated 3d⁶ system of the Co³⁺ ion, taking into account the crystal-field interactions, with a relatively weak trigonal distortion, and the relativistic spin-orbit interaction. We have calculated from really first-principles the relevant crystal-field interactions. With the discrete electronic structure for 3d electrons we have described the magnetic properties (the value of the magnetic moment and its direction). The moment direction is determined by the local off-octahedral trigonal distortion proving the single-ion origin of the magnetocrystalline anisotropy. We evaluated the orbital moment and the strength of spin interactions responsible for the formation of the magnetic state. Our studies indicate that calculations of the electronic structure of a 3d compound for the physically-adequate description of the magnetic properties has to be performed at the meV scale.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 391-393
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
EPR Study of Fe$\text{}^{3+}$ Paramagnetic Centers in Doped Triglycine Sulphate Crystals
Autorzy:
Łoś, Sz.
Trybuła, Z.
Powiązania:
https://bibliotekanauki.pl/articles/2030426.pdf
Data publikacji:
2002-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.Fc
77.80.-e
Opis:
This paper presents EPR study of Fe$\text{}^{3+}$ in triglycine sulphate doped with Fe$\text{}^{3+}$ crystal. Fe$\text{}^{3 +}$ ion is in a high spin state S=5/2. EPR signal can be detected only below 200 K. At 4.2 K the EPR spectrum results from three non-equivalent sites of Fe$\text{}^{3+}$ ions. The spin Hamiltonian: H=β BĝS+D[S$\text{}_{z}^{2}$-(1/3)S(S+1)]+E(S$\text{}_{x}^{2}$-S$\text{}_{y}^{2}$) has been applied to describe the spectrum. The zero field splitting parameter in this case fulfills the condition: D≫hν. An experimental spectrum reflects clearly only two resonance transitions: |±1/2ã (the lowest Kramers doublet) and |±3/2〉 (the middle Kramers doublet). The iron complexes occupy interstitial positions in the crystal with distorted octahedral or tetrahedral co-ordination.
Źródło:
Acta Physica Polonica A; 2002, 101, 2; 279-287
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Unusual Time Dependence of Magnetization Relaxation in MBE Grown Epilayer of CdMnTe
Autorzy:
Witowski, A. M.
Moll, H. P.
Wyder, P.
Karczewski, G.
Wojtowicz, T.
Kossut, J.
Powiązania:
https://bibliotekanauki.pl/articles/1934049.pdf
Data publikacji:
1995-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.60.Wm
76.30.Fc
Opis:
The temporal behavior of the magnetization due to the spin-lattice relaxation for bulk and MBE grown epilayer of CdMnTe is compared. The time dependence of the epilayer magnetization changes (dM/dt) is nonmonotonic. After the main part, a second structure appears. It can be explained only by the assumption of energy storage and a delayed additional rise of specimen temperature. The nature of the storage is unknown.
Źródło:
Acta Physica Polonica A; 1995, 88, 5; 953-956
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the Tunneling Among Shallow and Deep Centers in ZnS
Autorzy:
Zakrzewski, A.
Sienkiewicz, A.
Powiązania:
https://bibliotekanauki.pl/articles/1879959.pdf
Data publikacji:
1991-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.20.Jv
76.30.Fc
Opis:
Results of the photo-ESR studies of recharging processes due to tunneling in ZnS:Cu crystals are presented. It was found that the tunneling among shallow and deep centers seems to be a second order effect in the overall photoluminescence quenching in ZnS by transition metal impurities.
Źródło:
Acta Physica Polonica A; 1991, 79, 2-3; 251-254
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Hydrostatic Pressure on the Zero-Field Splitting in NiSnCl$\text{}_{6}$·6H$\text{}_{2}$O
Autorzy:
Krupska, A.
Krupski, M.
Powiązania:
https://bibliotekanauki.pl/articles/2035745.pdf
Data publikacji:
2003-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
62.50.+p
76.30.Fc
Opis:
The dependence of the crystal-field splitting parameter D in NiSnCl$\text{}_{6}$·6H$\text{}_{2}$O on hydrostatic pressure was determined by the electron paramagnetic resonance method, for the pressures up to 500 MPa. The derivative (∂D/∂p)$\text{}_{T}$ as well as the temperatures and pressures at which the D-parameter reaches zero, were determined. The molecular mechanism responsible for the temperature and pressure changes of the D-parameter is similar to that one observed in the isomorphic NiSiF$\text{}_{6}$·6H$\text{}_{2}$O.
Źródło:
Acta Physica Polonica A; 2003, 103, 5; 453-458
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spin-Lattice Relaxation Beyond the Debye Approximation
Autorzy:
Witowski, A. M.
Bardyszewski, W.
Kutter, Ch.
Wyder, P.
Witkowska, B.
Mycielski, A.
Powiązania:
https://bibliotekanauki.pl/articles/1877052.pdf
Data publikacji:
1995-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.Fc
63.20.Dj
Opis:
In this paper we present the results of magnetization relaxation in HgCdMnTe at high magnetic fields. In this mixed crystal the TA phonons have an energy lower than the spin splitting of the Mn^{2+} ground orbital singlet at about 20 T, which allows to check the effect of phonons with wave vectors from the edges of the Brillouin zone on the spin-lattice relaxation.
Źródło:
Acta Physica Polonica A; 1995, 87, 2; 533-535
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Orientation Dependent Spin-Lattice Relaxation in CdMnSe
Autorzy:
Witowski, A. M.
Strutz, T.
Wyder, P.
Powiązania:
https://bibliotekanauki.pl/articles/1877057.pdf
Data publikacji:
1995-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.Fc
63.20.Dj
Opis:
The magnetization dynamics of Cd$\text{}_{1-x}$Mn$\text{}_{x}$Se at 4.5 K as a function of magnetic field up to 22 T was measured using a nonresonant technique. For x = 0.01 the relaxation does not depend on orientation and in higher fields the relaxation rates are proportional to B$\text{}^{3}$. For x = 0.02 a dependence on orientation is observed. The difference does not depend on magnetic field. This suggests that either the interaction between Mn ions responsible for spin-lattice relaxation in Mn clusters is anisotropic, or the relaxing clusters are oriented in a given manner with respect to the c axis.
Źródło:
Acta Physica Polonica A; 1995, 87, 2; 536-538
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
EPR Study of Ammonium Nitrate Doped with Copper(II) Ions
Autorzy:
Wojtowicz, W.
Więckowski, A. B.
Powiązania:
https://bibliotekanauki.pl/articles/2043645.pdf
Data publikacji:
2005-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.50.Ks
76.30.Fc
Opis:
This work is devoted to a study of the structural changes in a single crystal of ammonium nitrate, NH$\text{}_{4}$NO$\text{}_{3}$, doped with copper(II) cations by electron paramagnetic resonance. Ammonium nitrate crystallizes at atmospheric pressure in several polymorphic forms, phase VII → V → IV → III → II → I → melt, with transition temperatures of 103 K, 255 K, 305 K, 357 K, 398 K, and 443 K, respectively. The aim of our work was to study the temperature phase transition V → IV at about 255 K using electron paramagnetic resonance technique. The electron paramagnetic resonance spectra were performed using an X-band spectrometer with microwave frequency of 9.4 GHz and magnetic modulation of 100 kHz in the temperature range of 153-296 K. For a single crystal the angular dependence of the copper(II) electron paramagnetic resonance spectra was measured at 293 K and 168 K. The anisotropic behaviour measured at 293 K points to the existence of one kind of two equivalent copper(II) complexes with inverse g and A tensors. A second pair of equivalent complexes also with inverse g and A tensors was observed. The minimal values of g-factors correspond to the maximum values of A. The angular dependence taken at 168 K shows the existence of two types of non-equivalent copper complexes which differ in comparison with the complexes observed at room temperature. The temperature dependence of the intensities of hyperfine structure lines for all copper(II) complexes observed shows a phase transition V → IV occurring in the temperature range of 237-246 K with a hysteresis. One of the hyperfine structure lines of a copper(II) complex measured at low temperatures shows a superhyperfine structure with line intensities 1:2:3:2:1 originating from the interaction of the copper $\text{}^{63,65}$Cu (I=3/2) nucleus with two $\text{}^{14}$N (I = 1) nuclei of two ammonia, NH$\text{}_{3}$, ligand molecules.
Źródło:
Acta Physica Polonica A; 2005, 108, 2; 395-401
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
NMR Analysis of Mg Ion Localization in $LiNbO_{3}$ Crystal
Autorzy:
Yatsenko, A.
Yevdokimov, S.
Sugak, D.
Solskii, I.
Powiązania:
https://bibliotekanauki.pl/articles/1550498.pdf
Data publikacji:
2010-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.Fc
76.30.Kg
77.84.Ek
Opis:
The analysis of cation sublattices population in magnesium doped $LiNbO_{3}$ crystals is carried out. It is shown that volume concentration of lithium vacancies $(V_{Li})$ monotonously increases with increasing of MgO content in the crystal up to the threshold value. A series of $LiNbO_{3}$ crystals with various concentration of $Mg^{2+}$ were investigated by $\text{}^{7}Li$ and $\text{}^{93}Nb$ Nuclear Magnetic Resonance (NMR). It is concluded that the peculiarities of NMR spectra in Mg-doped $LiNbO_{3}$ crystals can be explained by the formation of defect complexes including $Mg_{Li}$ ions and $V_{Li}$ on the shortest distances between them.
Źródło:
Acta Physica Polonica A; 2010, 117, 1; 166-169
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
FMR Study of Temperature Dependence of Magnetic Properties of Nanocrystalline $0.90(Fe_2O_3)$/0.10ZnO
Autorzy:
Guskos, N.
Glenis, S.
Zolnierkiewicz, G.
Typek, J.
Sibera, D.
Narkiewicz, U.
Powiązania:
https://bibliotekanauki.pl/articles/1492781.pdf
Data publikacji:
2011-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Tt
76.30.Fc
76.50.+g
Opis:
The nanocrystalline mixed system $0.90(Fe_2O_3)$/-0.10ZnO has been prepared by coprecipitation and calcination processes. The phase composition of samples was determined by X-ray diffraction. The studied nanocrystalline sample is dominated by phase $Fe_2O_3$ but very small amounts of ZnO and $ZnFe_2O_4$ phases were also identified. The ferromagnetic resonance investigations of the obtained sample have been carried out in the temperature range from liquid helium to room temperature. The asymmetrical and very intense magnetic resonance line was recorded at all temperatures. A significant shift of spectra towards lower magnetic fields with decreasing temperature was observed. A very good fitting by two Lorentzian functions has been obtained which suggested the existence of a strong anisotropic magnetic interaction. Some similarities in behaviour of ferromagnetic resonance parameters of the present sample and the $0.95Fe_2O_3Fe2O3$/0.05ZnO sample were noticed but the parameters values were essentially different. The gradients Δ $H_{r}$/Δ T (where $H_{r}$ is the resonance field), the broadening processes of the resonance lines as well as the line amplitudes were changing more intensely changing with temperature in comparison to sample $0.95Fe_2O_3Fe2O3$/0.05ZnO. The following values Δ $H_{r}$/Δ T are obtained: 16.7(1) Gs/K and 20.7(1) Gs/K over the 60 K temperatures where below 40 K is 41.5(1) Gs/K and 56.0(1) Gs/K. The reorientation processes were more active at low temperatures for smaller concentrations of magnetic nanoparticles.
Źródło:
Acta Physica Polonica A; 2011, 120, 6; 1070-1073
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Resonance Study of MnO/ZnO Nanopowders
Autorzy:
Guskos, N.
Zolnierkiewicz, G.
Typek, J.
Sibera, D.
Narkiewicz, U.
Łojkowski, W.
Powiązania:
https://bibliotekanauki.pl/articles/1492782.pdf
Data publikacji:
2011-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Tt
76.30.Fc
76.50.+g
Opis:
Fine particles n(MnO)/-(1-n)ZnO (n = 0.05 to 0.95) were prepared by wet chemistry method. According to X-ray diffraction analysis the obtained samples with n = 0.95, 0.90, 0.80, 0.70, 0.60 contained $Mn_3O_4$ and $ZnMn_2O_4$ phases, while samples with n = 0.05, 0.10, 0.20, 0.30, 0.40 and 0.50 contained $ZnMnO_3$ and ZnO phases. The mean crystalline size of $ZnMnO_3$ varied from 8 to 13 nm. The magnetic resonance investigations have been carried out at room temperature. Slightly asymmetric, broad and intense magnetic resonance line is recorded for all samples. The magnetic resonance spectra parameters showed marked differences depending on the composition index n. This could be explained by the variation of the magnetic susceptibility and a much slower evolution of spin relaxation, associated with the interaction of crystal field and superexchange interactions. Taking into account the values of magnetic resonance parameters, the investigated samples could be divided into two groups: these with the composition index n<0.50 and those with n>0.50. A detailed discussion of the magnetic properties of different phases in the n(MnO)/-(1-n)ZnO system is presented.
Źródło:
Acta Physica Polonica A; 2011, 120, 6; 1074-1079
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Some Electronic Properties of Sr$\text{}_{1-x}$A$\text{}_{x}$CuO$\text{}_{2+δ}$ where A=La, K, and Ca
Autorzy:
Onyszkiewicz, I.
Czarnecki, P.
Poltoracky, Yu. B.
Zimpel, M.
Powiązania:
https://bibliotekanauki.pl/articles/1929860.pdf
Data publikacji:
1994-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.30.+h
72.15.-v
76.30.Fc
Opis:
The electronic properties of Sr$\text{}_{1-x}$A$\text{}_{x}$CuO$\text{}_{2+δ}$ (A = La, K, Ca) were examined. The crystal structure of the synthesized compounds was identified as orthorhombic with some admixture of tetragonal phase. For Sr$\text{}_{1-x}$La$\text{}_{x}$CuO$\text{}_{2+δ}$ the insulator-metal like transition was observed with increasing La content. The d$\text{}_{x²-y²}$ ground state of Cu ions was deduced from electron spin resonance measurements. The electronic state of Cu ions and their surrounding local symmetry was also found to be La and oxygen content dependent.
Źródło:
Acta Physica Polonica A; 1994, 85, 2; 303-306
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High-Field EPR of Zn$\text{}_{1-x}$Cr$\text{}_{x}$Te
Autorzy:
Boonman, M. E. J.
Mac, W.
Wittlin, A.
Twardowski, A.
Demianiuk, M.
Powiązania:
https://bibliotekanauki.pl/articles/1933865.pdf
Data publikacji:
1995-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Pp
76.30.Fc
78.30.Fs
Opis:
High magnetic field electron paramagnetic resonance experiments have been performed on Zn$\text{}_{1-x}$Cr$\text{}_{x}$Te covering the energy range 1-7 cm$\text{}^{-1}$ in fields up to 20 T at T = 1.2 K. The static magnetic field was oriented along the (100), (110) and (111) crystallographic axes of the sample. Pronounced absorption lines for intra-chromium transitions have been observed for these different orientations, revealing a strong anisotropy due to a static Jahn-Teller distortion. The measured low energy level structure of the Cr$\text{}^{++}$ ion can be described by a cubic crystal field model including this distortion of the Cr centers.
Źródło:
Acta Physica Polonica A; 1995, 88, 5; 829-832
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Magnetic Field on Blue Anti-Stokes Luminescence of ZnSe:Cr Crystals
Autorzy:
Ivanov, V. Yu.
Semenov, Yu.G.
Surma, M.
Godlewski, M.
Powiązania:
https://bibliotekanauki.pl/articles/1950807.pdf
Data publikacji:
1996-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Gs
78.55.Et
76.30.Fc
Opis:
The results of photoluminescence and magneto-luminescence studies of chromium doped ZnSe crystals are presented for blue colour shallow donor-shallow acceptor pair photoluminescence, with a zero phonon line at 2.692 eV. This donor-acceptor pair photoluminescence is observed under photo-excitation with photon energies smaller than the emission energy (anti-Stokes luminescence) and dominates in the photoluminescence spectrum of ZnSe:Cr at the excitation energy about 2.41 eV and for temperature T<20 K. A quantum efficiency of this anti-Stokes luminescence is relatively large. It is of about 10$\text{}^{-3}$ at 0 T and increases with increasing magnetic field up to 7 T at temperature T=2 K. We relate the intensity of the anti-Stokes luminescence to a non-equilibrium concentration of photo-excited Cr$\text{}^{+}$ ions and propose that the rate of spin-dependent recombination of Cr$\text{}^{+}$ ions with free holes (decreases with increasing magnetic field) is responsible for the observed increase in the anti-Stokes luminescence intensity at higher magnetic fields.
Źródło:
Acta Physica Polonica A; 1996, 90, 4; 821-824
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nature of Blue Anti-Stokes Luminescence in ZnSe:Cr
Autorzy:
Ivanov, V. Yu.
Semenov, Yu. G.
Surma, M.
Godlewski, M.
Powiązania:
https://bibliotekanauki.pl/articles/1933759.pdf
Data publikacji:
1995-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.Fc
71.55.Gs
78.55.Et
Opis:
The mechanism of the anti-Stokes photoluminescence in ZnSe:Cr is discussed. It is shown that the two-step ionization transitions of Cr(2$\text{}^{+}$ ↔ 1$\text{}^{+}$) result in appearance of the blue anti-Stokes photoluminescence of ZnSe:Cr. There are also some indications that the Auger type co-operative process can contribute to the photoluminescence excitation.
Źródło:
Acta Physica Polonica A; 1995, 88, 4; 743-746
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fe$\text{}^{2+}$ → Fe$\text{}^{3+}$ Ionization Transition in ZnSe
Autorzy:
Surma, M.
Godlewski, M.
Surkova, T. P.
Powiązania:
https://bibliotekanauki.pl/articles/1929647.pdf
Data publikacji:
1993-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Gs
76.30.Fc
78.50.Ge
Opis:
Detailed photo-ESR study of iron and chromium impurities in ZnSe is presented. The energy level position of Fe$\text{}^{2+}\text{}^{/}\text{}^{3+}$ energy level is determined. The role of iron and chromium impurities in nonradiative recombination processes is discussed.
Źródło:
Acta Physica Polonica A; 1993, 84, 3; 547-550
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Role of Auger-Type Energy Transfer Processes in Quenching of Anti-Stokes Emission in Chromium and Iron Doped ZnSe: ODMR, Optical and Time-Resolved Study
Autorzy:
Ivanov, V. Yu.
Karczewski, G.
Godlewski, M.
Omel'chuk, A. R.
Belyaev, A. E.
Zhavoronkov, N. V.
Powiązania:
https://bibliotekanauki.pl/articles/2036871.pdf
Data publikacji:
2003-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Gs
78.55.Et
76.30.Fc
Opis:
Energy up-conversion in chromium and iron doped ZnSe results in the appearance of an anti-Stokes luminescence. The process is efficient in ZnSe:Cr, but not in ZnSe:Fe. We conclude that very efficient three-center Auger processes in ZnSe:Fe quench the anti-Stokes luminescence emission. For chromium doped samples influence of the Auger mechanism is weaker, which we explain by less efficient carrier retrapping by Cr ions. We further discuss possibility of efficient pumping of infrared Cr-related emissions via Cr photoionization transition.
Źródło:
Acta Physica Polonica A; 2003, 103, 6; 695-701
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
NMR in Ferromagnetic Manganites
Autorzy:
Novák, P.
Powiązania:
https://bibliotekanauki.pl/articles/2037096.pdf
Data publikacji:
2004
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.15.Mb
76.30.Fc
71.70.Jp
Opis:
The conditions for observing NMR on the $\text{}^{55}$Mn nuclei in the ferromagnetic manganites are specified and the information which may be extracted from this NMR are discussed. As examples, the study of the order of the magnetic phase transition and the coexistence of different ferromagnetic phases in the ferromagnetic manganites are presented.
Źródło:
Acta Physica Polonica A; 2004, 105, 1-2; 57-67
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structural and Electron Paramagnetic Resonance Studies of (ZrO)$\text{}_{0.8}$(Y$\text{}_{2}$O$\text{}_{3}$)$\text{}_{0.2}$
Autorzy:
Shukla, N. L.
Sharma, S. V.
Chand, P.
Misra, B. N.
Powiązania:
https://bibliotekanauki.pl/articles/1929172.pdf
Data publikacji:
1993-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.16.-d
61.10.Lx
76.30.Fc
Opis:
The polycrystalline samples of copper and vanadium doped as well as undoped (ZrO)$\text{}_{0.8}$(Y$\text{}_{2}$O$\text{}_{3}$)$\text{}_{0.2}$ were synthesized and studied using X-ray diffraction, scanning electron microscopy and electron paramagnetic resonance (EPR) techniques in order to investigate their structural and magnetic behaviour. The effect of exposure to lithium vapours on the host lattice of these ceramic materials is also studied using EPR technique. It has been observed from X-ray diffraction study that the samples consist of mainly two phases monoclinic and tetragonal. The monoclinic phase is in dominant proportion. Scanning electron microscope study showed that the morphology of the samples is similar to each other. EPR studies showed interesting changes on diffusion of lithium into the lattice of the host materials.
Źródło:
Acta Physica Polonica A; 1993, 83, 4; 441-449
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Co$\text{}^{2+}$ Ions in ZnS$\text{}_{x}$Se$\text{}_{1-x}$:Co - ESR and Optical Studies
Autorzy:
Świątek, K.
Surkova, T. P.
Sienkiewicz, A.
Zakrzewski, A. J.
Godlewski, M.
Giriat, W.
Powiązania:
https://bibliotekanauki.pl/articles/1992580.pdf
Data publikacji:
1998-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Gs
76.30.Fc
78.55.Et
Opis:
The electron spin resonance of Co$\text{}^{2+}$ ions in ZnS$\text{}_{x}$Se$\text{}_{1-x}$:Co mixed crystals was measured at temperature of 3 K and microwave frequency of 9.47 GHz. Trigonal Co$\text{}_{Zn}^{2+}$-S center in the ZnS$\text{}_{0.001}$Se$\text{}_{0.999}$:Co crystal was identified and parameters of relevant spin Hamiltonian were determined. Influence of alloy disorder in the anion sublattice on the Co$\text{}_{Zn}^{2+}$ ground and first excited states is briefly discussed.
Źródło:
Acta Physica Polonica A; 1998, 94, 3; 593-596
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Properties of YBCO-PST Composites
Autorzy:
Andrzejewski, B.
Kaczmarek, A.
Stankowski, J.
Hilczer, B.
Marfaing, J.
Régnier, S.
Caranoni, C.
Powiązania:
https://bibliotekanauki.pl/articles/2014556.pdf
Data publikacji:
2000-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.80.Bj
74.25.Ha
76.30.Fc
Opis:
The magnetic properties of granular superconductor-insulator composites were investigated. The composites were random composition of the YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-δ}$ (YBCO) high-temperature superconductor and Pb(Sc$\text{}_{0.5}$Ta$\text{}_{0.5}$)O$\text{}_{3}$ (PST) ferroelectric insulator. The composites exhibited lower superconducting volume ratio than the YBCO content. For samples with YBCO content low enough no global (the whole sample) and local (separated grains) superconductivity was observed. The observed decay of the superconductivity, lowering of the critical temperature, and the increase in number of paramagnetic centres as PST content increases are explained assuming reaction among YBCO and PST phases and possible formation of an additional ones, which did not exist in the initial powders.
Źródło:
Acta Physica Polonica A; 2000, 98, 6; 739-746
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Study of Phases in FeVO₄-Co₃V₂O₈ System
Autorzy:
Guskos, N.
Zolnierkiewicz, G.
Pilarska, M.
Typek, J.
Blonska-Tabero, A.
Aidinis, C.
Powiązania:
https://bibliotekanauki.pl/articles/1030217.pdf
Data publikacji:
2017-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.40.Cx
75.50.Ee
76.30.Fc
Opis:
Magnetic properties of four nFeVO₄/(1-n)Co₃V₂O₈ samples obtained in reactions between FeVO₄ and Co₃V₂O₈ (n = 0.96, 0.86, 0.84 and 0.83, samples designated S1, S3, S4, S5, respectively) have been investigated by DC magnetisation in field cooling and zero-field-cooling modes and EPR. DC magnetic susceptibility showed paramagnetic behavior of all samples in high-temperature range (T > 20 K) and transition to antiferromagnetic state at 16-18 K (depending on sample iron content). Additional magnetic freezing at 8 K was registered for S3-S5 samples containing larger amount of cobalt. The Curie-Weiss law in 100-300 K temperature range indicates that Co²⁺ is in the high-spin state (S = 3/2). From the parameters of the hysteresis loop observed for the samples it was calculated that 0.58% of all magnetic (Fe³⁺, Co²⁺) ions were involved in the ferromagnetic states. EPR spectra of the samples were recorded in high temperature range (T > 90 K). The temperature dependence of the spectral parameters (resonance field, linewidth, integrated intensity) suggested the Fe³⁺ high-spin ions coupled by antiferromagnetic interaction and clusters of ions play major role in EPR spectra.
Źródło:
Acta Physica Polonica A; 2017, 132, 1; 24-30
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigations on the Anisotropic g Factors of the $Ni^{3+}$ Site in $La_2Ni_{0.5}Li_{0.5}O_4$
Autorzy:
Kuang, M.
Wu, S.
Zhang, Z.
Song, B.
Powiązania:
https://bibliotekanauki.pl/articles/1400149.pdf
Data publikacji:
2013-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.Fc
71.70.Ch
75.10.Dg
Opis:
The anisotropic g factors $g_{∥}$ and $g_{⊥}$ of $La_2Ni_{0.5}Li_{0.5}O_4$ are theoretically investigated using the perturbation formulae of the g factors for a low spin $(S=1//2) 3d^7$ ion in tetragonally elongated octahedra. The studied $Ni^{3+} (3d^7)$ center arises from the original $Ni^{2+}$ capturing one hole by $Li^{+}$ doping. The positive anisotropy $\Delta g (= g_{⊥}-g_{∥})$ can be ascribed to the lowest $\text{}^2 A_{1g}$ state due to the obvious (about 0.14 Å) tetragonal elongation of the oxygen octahedron around the $Ni^{3+}$ site via the Jahn-Teller effect, and the effective magnetic moment is also interpreted in a uniform way. The calculated results show good agreement with the experimental data, and the imperfection of the previous studies based on various adjusted tetragonal energy splittings without correlating to the local structure of the magnetic center is thus overcome in this work.
Źródło:
Acta Physica Polonica A; 2013, 123, 4; 734-736
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigations on the Spin-Hamiltonian Parameters and Local Structure of the Orthorhombic $Cu^{2+}$ Center in $PbTiO_3$ Crystal
Autorzy:
Chao-Ying, Li
Li-Bin, Cheng
Xue-Mei, Zheng
Powiązania:
https://bibliotekanauki.pl/articles/1400511.pdf
Data publikacji:
2015-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.Fc
75.10.Dg
71.70.Ch
Opis:
The spin-Hamiltonian parameters (the g factors $g_{i}$ and the hyperfine structure constants $A_{i}$, i = x, y, z) and local structure of the $Cu^{2+}$ center in $PbTiO_{3}$ are theoretically studied by using the perturbation formulae of these parameters for a $3d^{9}$ ion in an orthorhombically elongated octahedra. The orthorhombic center is attributed to $Cu^{2+}$ occupying the host $Ti^{4+}$ site associated with a nearest-neighbouring oxygen vacancy $V_{O}$ along the c-axis, and the impurity $Cu^{2+}$ off-center displacement $\Delta Z_{L}$ ( ≈0.18 Å) is smaller than that of the host $Ti^{4+}$ site ($\Delta Z_{H}$≈ 0.3 Å). Meanwhile, the planar $Cu^{2+}-O^{2-}$ bonds are found to experience the relative variation ΔR ( ≈ 0.098 Å) along the a- and b-axes, respectively, due to the Jahn-Teller effect and the size mismatching substitution of $Ti^{4+}$ by $Cu^{2+}$. The theoretical spin-Hamiltonian parameters based on the above defect structure agree well with the observed values.
Źródło:
Acta Physica Polonica A; 2015, 127, 6; 1671-1675
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
EPR Study of Water Induced Decomposition of the SrCuO$\text{}_{2}$ and Sr$\text{}_{2}$CuO$\text{}_{3}$ Ceramics Surface. The Role of Carbon Dioxide
Autorzy:
Augustyniak-Jabłokow, M. A.
Yablokov, Yu. V.
Jacyna-Onyszkiewicz, I.
Ivanova, T. A.
Shustov, V. A.
Powiązania:
https://bibliotekanauki.pl/articles/2047737.pdf
Data publikacji:
2007-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Ee
76.30.Fc
81.05.Je
Opis:
Processes of SrCuO$\text{}_{2}$ and Sr$\text{}_{2}$CuO$\text{}_{3}$ ceramics decomposition induced by contact with water and carbon dioxide were studied by EPR. The dominant signals in the spectra were found to originate from Sr$\text{}_{2}$Cu(OH)$\text{}_{6}$ (for Sr$\text{}_{2}$CuO$\text{}_{3}$) and SrCu(OH)$\text{}_{4}$·H$\text{}_{2}$O (for SrCuO$\text{}_{2}$) compounds. The thermally induced conversion of SrCu(OH)$\text{}_{4}$·H$\text{}_{2}$O into Sr$\text{}_{2}$Cu(OH)$\text{}_{6}$ was analysed, and its product CuO was found to exist in the nanocrystalline form. The presence of CO$\text{}_{2}$, reacting with Sr(OH)$\text{}_{2}$, was shown to modify the decomposition process leading to the appearance of SrCu(OH)$\text{}_{4}$·H$\text{}_{2}$O, some hydroxycarbonates and Cu(OH)$\text{}_{2}$ on the surface of ceramics studied. At temperatures higher than 300ºC CuO reacts back with Sr(OH)$\text{}_{2}$. For the samples being in contact with atmospheric moisture this compound, deposited on a surface of SrCuO$\text{}_{2}$, decomposes to Sr$\text{}_{2}$Cu(OH)$\text{}_{6}$. The presence of the antiferromagnetic compounds Cu(OH)$\text{}_{2}$, CuO, and Cu$\text{}_{2}$[(OH)$\text{}_{2}$CO$\text{}_{3}$] in the samples can influence the results of magnetic measurements of the studied ceramics.
Źródło:
Acta Physica Polonica A; 2007, 112, 3; 525-536
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
EPR Study of the Phase Transition in Dimethylammonium Gallium Sulfate Hexahydrate
Autorzy:
Hrabański, R.
Janiec-Mateja, M.
Czapla, Z.
Powiązania:
https://bibliotekanauki.pl/articles/2043560.pdf
Data publikacji:
2005-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.70.Kb
76.30.Fc
77.80.-e
Opis:
X-band electron paramagnetic resonance investigations of single crystals of Cr$\text{}^{3+}$-doped dimethylammonium gallium sulphate hexahydrate are presented from room temperature down to 110 K. The crystal undergoes a order-disorder phase transition to ferroelectric phase at 134 K and additionally a first-order transition into a low temperature non-ferroelectric phase at T$\text{}_{c2}$=116 K. The spin-Hamiltonian parameters were determined for paraelectric and ferroelectric phases. The spin-Hamiltonian parameters in the paraelectric phase are: g=1.982±0.002, b$\text{}_{2}^{0}$=(890±10)×10$\text{}^{-4}$ cm$\text{}^{-1}$, b=(386±15)×10$\text{}^{-4}$ cm$\text{}^{-1}$. Remarkable EPR line width changes confirm the order-disorder character of the ferroelectric phase transition. Additionally observed triplet lines demonstrate freezing-out of dimethylammonium reorientations which can be considered as a prime reason for this transition similarly as observed in dimethylammonium aluminium sulfate hexahydrate.
Źródło:
Acta Physica Polonica A; 2005, 108, 2; 283-290
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structure Characterization and Catalytic Properties of Cr$\text{}_{2}$O$\text{}_{3}$ Doped with MgO Supported on MgF$\text{}_{2}$
Autorzy:
Goslar, J.
Wojciechowska, M.
Zieliński, M.
Tomska-Foralewska, I.
Przystajko, W.
Powiązania:
https://bibliotekanauki.pl/articles/2043607.pdf
Data publikacji:
2005-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.Fc
68.43.Fg
82.65.+r
Opis:
A characterization of double oxide systems containing Cr$\text{}_{2}$O$\text{}_{3}$ doped with MgO and supported on MgF$\text{}_{2}$ was carried out. The catalysts were prepared by impregnation and co-impregnation methods and characterized by the Brunauer-Emmett-Teller method, EPR, and temperature programmed reduction. The results proved the interactions between supported oxides and the presence of spinel-like phase after treatment at 400ºC. Magnesium oxide clearly influences the catalytic activity as well as selectivity of chromium catalysts supported on MgF$\text{}_{2}$. The MgO-Cr$\text{}_{2}$O$\text{}_{3}$/MgF$\text{}_{2}$ systems were active and selective in the reaction of CO oxidation at the room temperature and in the dehydrogenation of cyclohexene.
Źródło:
Acta Physica Polonica A; 2005, 108, 2; 323-330
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Delocalization of the $Cu^{2+}$ Unpaired Electron on the Next Nearest Ligands in $Sr_2Pd_{0.99}Cu_{0.01}O_3$ Ceramics
Autorzy:
Augustyniak-Jabłokow, M.
Yablokov, Y.
Jacyna-Onyszkiewicz, I.
Ivanova, T.
Shustov, V.
Polovniak, V.
Powiązania:
https://bibliotekanauki.pl/articles/1812323.pdf
Data publikacji:
2008-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
33.15.Pw
73.20.Jc
76.30.Fc
Opis:
Supertransferred hyperfine interactions between the $Cu^{2+}$ unpaired electron and the $\text{}^{105}Pd$ nuclei in the $Sr_2Pd_{0.99}Cu_{0.01}O_3$ ceramic were studied by the EPR method. The spectrum of isolated -Pd-O-$CuO_2$-O-Pd- units ($g_∥$ = 2.280±0.001; $g_⊥$ = 2.040±0.001; $A_∥(\text{}^{63}Cu)$ = 13 mT±0.1; $A_∥(\text{}^{65}Cu)$ = 13.9 ±0.1 mT; $A_⊥(\text{}^{63,65}Cu)$ = 0.0 mT) overlaps the signal from small groups of exchange coupled $Cu^{2+}$ ions ($g_∥$ = 2.278±0.002; $g_⊥$ = 2.041±0.001). The isotropic contribution was shown to dominate in the Cu-Pd supertransferred interactions ($A_∥(\text{}^{105}Pd) = A_⊥ (\text{}^{105}Pd)$ = 1 mT = $a_\text{iso}$ Pd).
Źródło:
Acta Physica Polonica A; 2008, 114, 1; 197-201
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigations of the Optical and EPR Spectra for $Cr^{3+}$ Ions in Diammonium Hexaaqua Magnesium Sulphate Single Crystal
Autorzy:
Wei, Q.
Powiązania:
https://bibliotekanauki.pl/articles/1535818.pdf
Data publikacji:
2010-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.Fc
71.70.Ch
71.55.Ht
Opis:
The relations between spin-Hamiltonian parameters and local structure around $Cr^{3+}$ in diammonium hexaaqua magnesium sulphate single crystal were established. On the basis of this, the spin-Hamiltonian parameters, optical spectra and the local structure were investigated successfully. The calculated results are in good agreement with experimental data. This shows that the distortion model adopted in this paper is reasonable.
Źródło:
Acta Physica Polonica A; 2010, 118, 4; 670-672
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
ESR Study of the Magnetic Properties of the CdTe/CdMnTe Multi Quantum Wells
Autorzy:
Surma, M.
Godlewski, M.
Waag, A.
Powiązania:
https://bibliotekanauki.pl/articles/1929641.pdf
Data publikacji:
1993-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.20.Dx
75.70.Fr
76.30.Fc
Opis:
The results of electron spin resonance investigations of bulk Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te and of molecular beam epitaxy grown CdTe/CdMnTe single 2 μm thick layer and multi quantum well with Mn concentrations of about x = 0.10 are compared. The Mn$\text{}^{2+}$ electron spin resonance spectrum of the MQW CdTe/CdMnTe shows several features different from those observed in the CdMnTe bulk sample. The Mn$\text{}^{2+}$ resonance shows a small anisotropy of position and width with the anisotropy axis normal to the heterointerface. The temperature dependence of the width of the electron spin resonance line is also different from that observed for the bulk and for the thick single layer.
Źródło:
Acta Physica Polonica A; 1993, 84, 3; 543-546
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Origin of EPR Signals in SrCuO$\text{}_{2}$ Ceramics
Autorzy:
Augustyniak-Jabłokow, M. A.
Yablokov, Yu. V.
Ivanova, T. A.
Jacyna-Onyszkiewicz, I.
Shustov, V. A.
Powiązania:
https://bibliotekanauki.pl/articles/2043623.pdf
Data publikacji:
2005-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Ee
76.30.Fc
81.05.Je
Opis:
The origin and thermal evolution of the EPR signals in SrCuO$\text{}_{2}$ ceramics are studied. It has been shown that the EPR signals observed in this ceramic material are due to contamination with other phases. The axial signal is due to SrCu(OH)$\text{}_{4}$·H$\text{}_{2}$O, which is a product of water reactions with SrCuO$\text{}_{2}$.
Źródło:
Acta Physica Polonica A; 2005, 108, 2; 345-351
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparison of Microscopic Mechanisms of Blue Anti-Stokes Luminescence in Undoped and Chromium Doped ZnSe Crystals
Autorzy:
Ivanov, V. Yu.
Omel'chuk, A.
Godlewski, M.
Powiązania:
https://bibliotekanauki.pl/articles/1991537.pdf
Data publikacji:
1998-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Gs
78.55.Et
76.30.Fc
Opis:
Anti-Stokes luminescence is observed in chromium doped and in undoped ZnSe crystals. In the former case anti-Stokes luminescence is due to two complementary ionization transitions of Cr ions. In the latter case two-photon absorption becomes important at a high excitation density.
Źródło:
Acta Physica Polonica A; 1998, 94, 3; 365-368
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
EPR Study of Dealuminated HY Zeolite and Silica Containing Cu-Mn-Zn Spinels: The Effect of Support
Autorzy:
Decyk, P.
Więckowski, A.
Najder-Kozdrowska, L.
Bilkova, I.
Ziółek, M.
Powiązania:
https://bibliotekanauki.pl/articles/1030220.pdf
Data publikacji:
2017-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.43.-h
76.30.-v
76.30.Fc
82.75.Vx
Opis:
A mixture of antiferromagnetic Cu_{1.4}Mn_{1.6}O₄ and Cu_{0.5}Zn_{0.5}Mn₂O₄ or/and ZnMn₂O₄ spinels was prepared. Dealuminated HY zeolite and silica were doped by these Cu-Mn-Zn spinels. The materials were investigated by X-ray diffraction, the Fourier transform infrared spectroscopy and EPR spectroscopy. Additionally, all the samples were tested for their activity for isopropyl alcohol dehydration/dehydrogenation. Three EPR signals were observed for Cu-Mn-Zn/dealuminated HY and Cu-Mn-Zn/SiO₂ samples at 293 K. In contrast to the spectra recorded at 293 K, only one broad line attributed to Cu-Mn-Zn spinels was visible at 77 K. The EPR signal from pure Cu-Mn-Zn spinels consists only of a single broad line when recorded at 293 K, whereas at 77 K the line is narrower. For all samples subjected to evacuation at high vacuum up to 573 K, the Cu-Mn-Zn spinels were stable. The evacuation at 673 K resulted in a rapid lowering of the intensity of EPR spectrum.
Źródło:
Acta Physica Polonica A; 2017, 132, 1; 38-44
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Theoretical Explanations of the Optical Band Positions and Local Structure for $Cu^{2+}$ Centers in $ZnO-Bi_{2}O_{3}-B_{2}O_{3}-CuO$ Glasses
Autorzy:
Yuan, M.
Powiązania:
https://bibliotekanauki.pl/articles/1377767.pdf
Data publikacji:
2014-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.72.Bb
75.10.Dg
76.30.-v
76.30.Fc
Opis:
The local structure, two optical band positions and three electronic spin resonance parameters for $Cu^{2+}$ centers at the tetragonally-distorted octahedral sites in $ZnO-Bi_2O_3-B_2O_3-CuO$ glasses are calculated from the high-order perturbation method based on the two-spin-orbit-parameter model, where the contributions from both the spin-orbit coupling parameters of central $d^{n}$ ion and ligand ion are included. The theoretical results are in good agreement with the experimental values. The calculations show that the high-order perturbation method based on the two-spin-orbit-parameter model is effective in the explanations of optical spectra, electronic spin resonance parameters and local distortion structure for $d^{9}$ ions in glasses.
Źródło:
Acta Physica Polonica A; 2014, 126, 6; 1293-1295
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Conversions of the Second-Rank Zero Field Splitting Parameters Measured Assuming the Fictitious Spin S=1 to those for the Effective Spin S̃=2
Autorzy:
Kozanecki, M.
Rudowicz, C.
Powiązania:
https://bibliotekanauki.pl/articles/1030215.pdf
Data publikacji:
2017-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.70.Ch
75.10.Dg
76.30.-v
76.30.Fc
Opis:
We investigate feasibility of comparison between the zero field splitting parameters obtained experimentally based on the spin Hamiltonian with the fictitious spin S'=1 and those with the effective spin S̃=2. The former zero field splitting parameters have recently been measured for Fe²⁺ ions in forsterite Mg₂SiO₄, whereas the latter zero field splitting parameters are available in literature, e.g. for Fe²⁺ and Cr²⁺ (S̃=2) ions. It turns out that no unique direct comparison is feasible and hence appropriate conversion relations need to be derived. Methodology for such conversions is outlined. Various combinations of the possible energy level schemes for the spin S̃=2 and S'=1 are briefly described. Illustrative preliminary results concerning appropriate conversions of the second-rank zero field splitting parameters measured by high-frequency EMR for Fe²⁺ in natural and synthetic forsterite are presented. Detailed results and full analysis will be given elsewhere.
Źródło:
Acta Physica Polonica A; 2017, 132, 1; 11-14
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Implications of Invalid Conversions between Crystal-Field Parameters and Zero-Field Splitting Ones Used in Superposition Model
Autorzy:
Rudowicz, C.
Karbowiak, M.
Powiązania:
https://bibliotekanauki.pl/articles/1365340.pdf
Data publikacji:
2014-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.-v
76.30.Fc
71.70.Ch
75.10.Dg
Opis:
The methodology used in recent study of the zero-field splitting parameters of $Cr^{3+}$ ions at various orthorhombic symmetry sites in $LiKSO_4$ by Pandey and Kripal is critically commented on. We argue that the crystal field parameters, $B_{kq}$, in the Wybourne notation, which were calculated using the superposition model for $Cr^{3+}$ ions in $LiKSO_4$, may only be converted into the crystal field parameters in the Stevens notation. Regrettably, the authors have also converted the latter parameters supposedly into the zero-field splitting parameters D and E in the conventional notation. Such direct conversions are fundamentally incorrect and constitute factual invalid usage of the conversion relations between the crystal field (ligand field) parameters and the zero-field splitting ones. The cases of an implied usage of the invalid conversion relations between the crystal field parameters and the zero-field splitting parameters occurring in recent literature are also outlined. Pandey and Kripal have found the zero-field splitting parameters theoretically evaluated in this way to be in good agreement with the experimental values. However, the faulty methodology renders the conclusion that $Cr^{3+}$ ions enter into the $LiKSO_4$ lattice at the substitutional $K^{+}$ sites unjustified. Several other conceptual problems arising from misinterpretations of the crucial notions identified therein are also discussed and clarified.
Źródło:
Acta Physica Polonica A; 2014, 125, 5; 1215-1219
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Origin of Ultrafast Component of Photoluminescence Decay in Nanostructures Doped with Transition Metal or Rare-Earth Ions
Autorzy:
Godlewski, M.
Yatsunenko, S.
Ivanov, V. Yu.
Khachapuridze, A.
Świątek, K.
Goldys, E. M.
Phillips, M. R.
Klar, P. J.
Heimbrodt, W.
Powiązania:
https://bibliotekanauki.pl/articles/2041630.pdf
Data publikacji:
2005-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Gs
76.30.Fc
76.70.Hb
78.55.Et
Opis:
Bulk samples, layers, quantum well, and quantum dot structures of II-Mn-VI samples all show coexistence of slow and fast components of Mn$\text{}^{2+}$ photoluminescence decay. Thus, fast photoluminescence decay cannot be related to low dimensionality of a host material. This also means that the model of the so-called quantum confined atom is incorrect. Based on the results of time-resolved photoluminescence and optically detected magnetic resonance investigations we relate the observed lifetime decrease in Mn$\text{}^{2+}$ intra-shell transition to spin dependent magnetic interactions between localized spins of Mn$\text{}^{2+}$ ions and between Mn$\text{}^{2+}$ ions and spins/magnetic moments of free carriers. The latter mechanism is enhanced in nanostructures.
Źródło:
Acta Physica Polonica A; 2005, 107, 1; 65-74
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spin Dependent Interactions of Free Carriers and Manganese Ions in Nanostructures of Wide Band Gap II-Mn-VI Semiconductors - Mechanism of Lifetime Reduction
Autorzy:
Yatsunenko, S.
Khachapuridze, A.
Ivanov, V. Yu.
Godlewski, M.
Khoi, Le Van
Gołacki, Z.
Karczewski, G.
Goldys, E. M.
Phillips, M.
Klar, P. J.
Heimbrodt, W.
Powiązania:
https://bibliotekanauki.pl/articles/2036034.pdf
Data publikacji:
2003-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Gs
76.30.Fc
76.70.Hb
78.55.Et
Opis:
Based on the results of optically detected magnetic resonance and time-resolved investigations we relate the observed lifetime shortening of intra-shell Mn$\text{}^{2+}$ emission to spin dependent magnetic interactions between localized spins of Mn$\text{}^{2+}$ ions and spins/magnetic moments of free carriers. We show that this mechanism is active in both bulk and in low dimensional structures, such as quantum wells, quantum dots, and nanostructures.
Źródło:
Acta Physica Polonica A; 2003, 103, 6; 643-648
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mechanism of Radiative Mn$\text{}^{2+}$ Intra-Shell Recombination in Bulk ZnMnS
Autorzy:
Ivanov, V. Yu.
Godlewski, M.
Yatsunenko, S.
Khachapuridze, A.
Li, M. S.
Gołacki, Z.
Powiązania:
https://bibliotekanauki.pl/articles/2027501.pdf
Data publikacji:
2001-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Gs
76.30.Fc
76.70.Hb
78.55.Et
Opis:
Origin of a fast component of the photoluminescence decay of Mn$\text{}^{2+}$ intra-shell $\text{}^{4}$T$\text{}_{1}$ → $\text{}^{6}$A$\text{}_{1}$ transition is discussed based on the results of photoluminescence, photoluminescence kinetics and optically detected magnetic resonance experiments performed for bulk ZnMnS samples with about 1% Mn fraction. It is demonstrated that a fast component of the photoluminescence decay, reported previously for quantum dot structure and related to quantum confinement effects, is also observed in bulk samples and is related by us to very efficient spin cross-relaxation effects.
Źródło:
Acta Physica Polonica A; 2001, 100, 3; 351-355
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Resonance Studies of the Origin of Ferromagnetism in Ga$\text{}_{1-x}$Mn$\text{}_{x}$As
Autorzy:
Fedorych, O. M.
Wilamowski, Z.
Potemski, M.
Byszewski, M.
Sadowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/2036029.pdf
Data publikacji:
2003-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Eq
76.30.Fc
75.50.Pp
75.30.Gw
Opis:
Different types of magnetic resonance observed in Ga$\text{}_{1-x}$Mn$\text{}_{x}$As reflect three different magnetic phases: para-, ferro-, and ferrimagnetic. Ferromagnet is characterized by single isotropic resonance line. A complex spectrum in ferrimagnet can be described by g factor equal to 1.44 and a sum of an axial and cubic anisotropy field. The axial field is by an order of magnitude greater than the cubic one. The complex structure of ferrimagnetic resonance is attributed to spin-wave resonance. Quantitative analysis of the dispersion of spin wave shows that the range of exchange coupling is very long, of the order of 25 nm, while spin-wave stiffness and the total exchange field are very small. The exchange field as evaluated from spin wave is by two orders of magnitude smaller than the Zener field corresponding to the critical temperature.
Źródło:
Acta Physica Polonica A; 2003, 103, 6; 607-612
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ferromagnetic, Ferrimagnetic and Spin-wave Resonances in GaMnAs Layers
Autorzy:
Fedorych, O.
Byszewski, M.
Wilamowski, Z.
Potemski, M.
Sadowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/2035590.pdf
Data publikacji:
2002
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Eq
76.30.Fc
75.50.Pp
75.30.Gw
Opis:
Molecular beam epitaxy grown Ga$\text{}_{1-x}$Mn$\text{}_{x}$As layers were investigated by means of magnetic resonances. With an increase in Mn concentration, x, the spectrum changes from the (i) paramagnetic one, with resolved fine and hyperfine structures, typical of S=5/2 spin of substitutional Mn$\text{}^{2+}$ ions, for very diluted alloy, via (ii) paramagnetic spectrum, where the fine and hyperfine structures are averaged by a long range Mn$\text{}^{2+}$-Mn$\text{}^{2+}$ exchange coupling, (iii) single, isotropic line of ferromagnetic resonance. Insulator to metal transition is accompanied with occurrence of (iv) a very complex spectrum of the ferrimagnetic resonance, accompanied with the well-resolved spin wave resonance. Reentrance to insulator phase for the most condensed alloys is accompanied with the reentrance to (v) ferromagnetic phase. The data confirm that the effective mass holes transfer the exchange interaction between localized Mn$\text{}^{2+}$ spins.
Źródło:
Acta Physica Polonica A; 2002, 102, 4-5; 617-625
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigations of the EPR and Optical Spectra for $VO^{2+}$ in $C_3H_7NO_2$ Powders
Autorzy:
Wei, Q.
Powiązania:
https://bibliotekanauki.pl/articles/1537793.pdf
Data publikacji:
2010-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.Fc
71.70.Ch
78.50.Ec
71.55.Ht
Opis:
The EPR and optical spectra for $VO^{2+}$ in $C_3 H_7 NO_2$ powders are calculated from complete diagonalization method and perturbation theory method, respectively. The calculated results are in good agreement with observed values. The negative signs of hyperfine structure constants $A_∥$ and $A_⊥$ for $VO^{2+}$ in $C_3 H_7 NO_2$ powders are also suggested from the calculations.
Źródło:
Acta Physica Polonica A; 2010, 117, 6; 962-964
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Complete Diagonalization Calculation of the Optical and EPR Data for the Tetragonal $Cu^{2+}$ Center in $Cu^{2+}$-Doped ZnSe Nanocrystals
Autorzy:
Wu, Xiao-Xuan
Zheng, Wen-Chen
Powiązania:
https://bibliotekanauki.pl/articles/1399131.pdf
Data publikacji:
2015-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.Fc
71.70.Ch
78.40.Fy
75.10.Dg
Opis:
By using the complete diagonalization (of energy matrix) method based on the cluster approach (where the admixture between the d orbitals of $d^{n}$ ion and p orbitals of ligands due to covalence effect is considered), the optical and electron paramagnetic resonance data (three optical band positions and four EPR parameters $g_{∥}$, $g_{⊥}$, $A_{∥}$, $A_{⊥}$) are calculated for the tetragonal $Cu^{2+}$ center in $Cu^{2+}$-doped poly vinyl alcohol (PVA) passivated ZnSe nanocrystals with the defect model of $Cu^{2+}$ in the interstitial octahedral site in ZnSe. The calculated results are near the experimental values. The tetragonal elongation of the $Cu^{2+}$ octahedral cluster in ZnSe nanocrystals is obtained. The results are discussed.
Źródło:
Acta Physica Polonica A; 2015, 127, 3; 795-798
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Theoretical Studies of ESR Parameters and Local Lattice Structure of the Vanadate-Lithium-Borate Glasses
Autorzy:
Feng, W.
Zhao, M.
Li, T.
Zhang, X.
Xue, J.
Powiązania:
https://bibliotekanauki.pl/articles/1419845.pdf
Data publikacji:
2012-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.70.Ch
75.10.Dg
61.72.Bb
76.30.Fc
Opis:
Electron spin resonance spectral parameters of $V^{4+}$ ions in vanadate-lithium-borate glasses have been calculated by the crystal-field theory. The theoretical results are $g_{∥ }$ = 1.940, $g_{⊥}$ = 1.983 and $A_{∥ } = -175 \times 10^{-4} cm^{-1},$ $A_{⊥} = -65 \times 10^{-4} cm^{-1}$ which are good agreement with the experimental values ($g_{∥ }$ = 1.939(3), $g_{⊥}$ = 1.998(3) and $A_{∥ } = (170.6-176.4) \times 10^{-4} cm^{-1},$ $A_{⊥} = (61.3-71.4) \times 10^{-4} cm^{-1}$). In addition, the bond lengths of the local lattice structure are, respectively, $R_{∥ }$ = 1.5 Å and $R_{⊥}$ = 1.95 Å which have been shown to have a compressed tetrahedral geometry along the $C_4$ axis.
Źródło:
Acta Physica Polonica A; 2012, 122, 1; 167-169
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mn Impurity in Bulk GaAs Crystals
Autorzy:
Pawłowski, M.
Piersa, M.
Wołoś, A.
Palczewska, M.
Strzelecka, G.
Hruban, A.
Gosk, J.
Kamińska, M.
Twardowski, A.
Powiązania:
https://bibliotekanauki.pl/articles/2044520.pdf
Data publikacji:
2005-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Eq
72.20.Ee
75.50.Pp
76.30.Fc
Opis:
Magnetic and electron transport properties of GaAs:Mn crystals grown by Czochralski method were studied. Electron spin resonance showed the presence of Mn acceptor A in two charge states: singly ionized A$\text{}^{-}$ in the form of Mn$\text{}^{2+}$(d$\text{}^{5}$), and neutral A$\text{}^{0}$ in the form of Mn$\text{}^{2+}$(d$\text{}^{5}$) plus a bound hole (h). It was possible to determine the relative concentration of both types of centers from intensity of the corresponding electron spin resonance lines. Magnetization measured as a function of magnetic field (up to 6 T) in the temperature range of 2-300 K revealed overall paramagnetic behavior of the samples. Effective spin was found to be about 1.5 value, which was consistent with the presence of two types of Mn configurations. In most of the studied samples the dominance of Mn$\text{}^{2+}$(d$\text{}^{5}$)+h configuration was established and it increased after annealing of native donors. The total value of Mn content was obtained from fitting of magnetization curves with the use of parameters obtained from electron spin resonance. In electron transport, two mechanisms of conductivity were observed: valence band transport dominated above 70 K, and hopping conductivity within Mn impurity band at lower temperatures. From the analysis of the hopping conductivity and using the obtained values of the total Mn content, the effective radius of Mn acceptor in GaAs was estimated as a = 11±3Å.
Źródło:
Acta Physica Polonica A; 2005, 108, 5; 825-830
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigations of the Optical Band Positions and Spin-Hamiltonian Parameters for the Rhombic $VO^{2+}$ Complex in CsCl Crystal
Autorzy:
Fang, W.
Zheng, W.
Yang, D.
Tang, H.
Powiązania:
https://bibliotekanauki.pl/articles/1365269.pdf
Data publikacji:
2014-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.70.Ch
75.10.Dg
61.72.Bb
76.30.Fc
Opis:
The optical band positions and spin-Hamiltonian parameters (g factors $g_{i}$ and hyperfine structure constants $A_{i}$, where i=x, y, z) of the rhombic $VO^{2+}$ complex in CsCl crystal are calculated together from two theoretical methods. One is the complete diagonalization (of energy matrix) method and another is the perturbation theory method. The calculated results from the two methods coincide and are in reasonable agreement with the experimental values. So, both methods are effective in the explanations of optical and electron paramagnetic resonance (EPR) data for $d^1$ ions in crystals. The calculations also suggest that in $d^1$ rhombic octahedra the ground state is almost a pure | $d_{xy}$ ⟩ state. This point is different from that of conjugate $d^9$ (e.g., $Cu^{2+}$) ions in rhombic octahedra where the ground state should be an admixture of ground and first excited states.
Źródło:
Acta Physica Polonica A; 2014, 125, 5; 1206-1209
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Microwave X-Band Resonances in Doped Cd₂Nb₂O₇ Monocrystals
Autorzy:
Waplak, S.
Ostrowski, A.
Wencka, M.
Bednarski, W.
Powiązania:
https://bibliotekanauki.pl/articles/1030214.pdf
Data publikacji:
2017-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.Fc
77.22.Ch
77.80.B-
77.84.Ek
Opis:
Cadmium pyroniobiate (CNO) is the ferroic material with unusual diffuse phase diagram which includes both relaxor and nanocluster domains. We present the data for CNO crystals with several admixtures of paramagnetic ions studied on X and S microwave bands at zero-external magnetic field and classical EPR conditions. Our results lead to an assertion of a ferroelectric resonance effect due to "electronic ferroelectricity". The data fit well to the Falicov-Kimball theoretical model applicable to strongly-correlated-electron or mixed-valence systems.
Źródło:
Acta Physica Polonica A; 2017, 132, 1; 7-11
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A unified calculation of the optical and EPR spectral data for the trigonal Cr³⁺ center in Cr³⁺-doped α-RbAl(SO₄)₂·12H₂O alum crystal
Autorzy:
Li, Xiao-Wu
Mei, Yang
Wei, Cheng-Fu
Zheng, Wen-Chen
Powiązania:
https://bibliotekanauki.pl/articles/1070555.pdf
Data publikacji:
2016-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.70.Ch
76.30.Fc
78.40.Ha
78.55.Hx
Opis:
The optical band positions and the spin-Hamiltonian parameters (g factors g_{∥}, g_{⊥}, and zero-field splitting parameter D) of alum α-RbAl(SO₄)₂·12H₂O:Cr³⁺ are calculated by diagonalizing the 120× 120 complete energy matrix based on the two-spin-orbit-coupling-parameter model. The model takes into account not only the contributions due to the spin-orbit-coupling parameter of central d^{n} ion in the conventional crystal field theory, but also those due to ligands via covalence effect. The calculation indicates that the fourteen observed spectral data (eleven optical band positions and three spin-Hamiltonian parameters) can be reasonably and uniformly explained with four adjustable parameters (the Racah parameters B, C, intrinsic parameter A̅₄(R) in the superposition model, and the trigonal distortion angle β). The calculations also suggest that contrary to the previous findings, the trigonal distortion of Cr³⁺ (entering the Al³⁺ site in the host crystal) center in α-RbAl(SO₄)₂·12H₂O is induced mainly by the oxygen (or water) octahedron around the Cr³⁺ ion rather than the more distant neighbors.
Źródło:
Acta Physica Polonica A; 2016, 129, 3; 340-343
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Explanation of the Optical Spectra and Spin-Hamiltonian Parameters for Nickel(II) in Cadmium Bromide Crystal
Autorzy:
Gong, J.
Wang, L.
Feng, W.
Yang, X.
Zhang, F.
Powiązania:
https://bibliotekanauki.pl/articles/1493631.pdf
Data publikacji:
2011-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.70.Ch
75.10.Dg
61.72.Bb
76.30.Fc
Opis:
Based on crystal- and ligand-field theory, double-spin-orbital coupling approach was used to analyze the crystal-field energy levels and spin-Hamiltonian parameters of $Ni^{2+}$ ion at trigonal site in $CdBr_2$. The local lattice distortion (Δ R and $τ_{Ni^{2+}}$) is estimated from the crystal field parameters; the crystal field energy Hamiltonian was diagonalized in the full basis consisting of 45 wave functions of the $Ni^{2+}$ ion. Results of calculations are in good agreement with experimental data. The reasonableness of the theoretical results is discussed.
Źródło:
Acta Physica Polonica A; 2011, 120, 3; 497-500
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spin-Spin and Spin-Other-Orbit Interactions of Spin-Hamiltonian Parameters for $3d^{2(8)}$ Ions in $Al_2O_3$ Crystals
Autorzy:
Wei, Q.
Guo, L.
Yang, Z.
Wei, B.
Powiązania:
https://bibliotekanauki.pl/articles/1505102.pdf
Data publikacji:
2011-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.Fc
71.70.Ch
75.10.Dg
71.55.Ht
Opis:
By considering weaker magnetic interactions (including spin-spin and spin-other-orbit interactions) in Hamiltonian, the spin-Hamiltonian parameters, including the zero-field splitting parameter D and g factors $(g_∥, g_⊥)$ for $3d^{2(8)}$ ions in $Al_2O_3$ crystals have been investigated. The results show that the contributions to D, $g_∥$ and $g_⊥$ from the spin-orbit interaction are dominant. The contributions from weaker magnetic interactions to D decrease (increase) with increasing charge of impurity ions for $3d^2 (3d^8)$ ions.
Źródło:
Acta Physica Polonica A; 2011, 119, 6; 857-859
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Diffusion on (ZrO$\text{}_{2}$)$\text{}_{0.8}$(Y$\text{}_{2}$O$\text{}_{3}$)$\text{}_{0.2}$ Ceramic
Autorzy:
Sharma, S. V.
Chand, P.
Powiązania:
https://bibliotekanauki.pl/articles/1933619.pdf
Data publikacji:
1995-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.16.-d
64.80.Gd
66.30.-h
76.30.Fc
81.20.Lb
Opis:
Effect of iodine and lithium diffusion on undoped and doped (with transition metal ions: Ti, V, Ni, Fe, Cu, Co and Mn) samples of polycrystalline (ΖrO$\text{}_{2}$)$\text{}_{0.8}$(Y$\text{}_{2}$O$\text{}_{3}$)$\text{}_{0.2}$ ceramic has been investigated using X-ray diffraction, scanning electron microscopy and electron paramagnetic resonance.
Źródło:
Acta Physica Polonica A; 1995, 88, 3; 503-509
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spin Hamiltonian parameters for Co²⁺ ions in PbMoO₄ crystal - interplay between the fictitious spin S=1/2 and the effective spin S̃ =3/2
Autorzy:
Piwowarska, D.
Kaczmarek, S.
Gnutek, P.
Rudowicz, C.
Powiązania:
https://bibliotekanauki.pl/articles/1055009.pdf
Data publikacji:
2017-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Dg
71.70.Ch
61.50.Ah
61.72.Hh
76.30.-v
76.30.Fc
Opis:
The interplay between the fictitious spin S' = 1/2 and the effective spin S̃=3/2 for Co²⁺(3d⁷) ions is considered. The available experimental data on the Ze g_{i}' factors for the two Co²⁺ complexes in PbMoO₄ obtained using the fictitious "spin" S'=1/2 description serve for determination of the Zeeman g_{i} factors corresponding to the effective spin S̃ =3/2. The second-rank zero-field splitting parameters D and E (S̃ = 3/2) are also indirectly determined from the experimental EMR data by employing the formulas arising from projection of the g_{i}(S̃=3/2) factors onto the g_{i}'(S' = 1/2) factors. The so-determined second-rank zero-field splitting parameters and g_{i}(S̃ = 3/2) factors will enable comparison with the respective quantities obtained in a subsequent paper using a combined modeling approach.
Źródło:
Acta Physica Polonica A; 2017, 132, 1; 73-76
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
EMR Data on Mn(III; S=2) Ions in MnTPPCl Complex Modelled by Microscopic Spin Hamiltonian Approach
Autorzy:
Tadyszak, K.
Rudowicz, C.
Powiązania:
https://bibliotekanauki.pl/articles/1030216.pdf
Data publikacji:
2017-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
33.35.+r
71.70.Ch
71.70.Ej
76.20.+q
76.30.-v
76.30.Fc
87.80.Lg
Opis:
The electron magnetic resonance data on high-spin (S =2) manganese(III) 3d⁴ ion in tetraphenylporphyrinato chloride complex (MnTPPCl) obtained by high-frequency techniques are reanalysed. Preliminary results of semiempirical modeling of the spin Hamiltonian parameters for Mn(III) in MnTPPCl are presented. The microscopic spin Hamiltonian approach is utilized to predict the zero-field splitting and the Zeeman electronic parameters. It is found that for Mn(III) ions in MnTPPCl matching the experimental spin Hamiltonian parameters and the theoretical ones based on the ligand-field energy levels (Δ_{i}) within the ⁵D multiplet only may not be suitable for this system. Contributions due to the levels arising from the higher-lying ³H multiplet need to be taken into account in order to determine the reasonable values of microscopic parameters describing Mn(III) ions in MnTPPCl.
Źródło:
Acta Physica Polonica A; 2017, 132, 1; 15-19
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of Genetic Algorithm for Extraction of the Parameters from Powder EPR Spectra
Autorzy:
Spałek, T.
Pietrzyk, P.
Sojka, Z.
Powiązania:
https://bibliotekanauki.pl/articles/2043399.pdf
Data publikacji:
2005-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
02.60.Pn
02.60.Ed
76.30.Fc
82.75.Mj
61.43.Gt
Opis:
The application of the stochastic genetic algorithm in tandem with the deterministic Powell method to automated extraction of the magnetic parameters from powder EPR spectra was described. The efficiency and robustness of such hybrid approach were investigated as a function of the uncertainty range of the parameters, using simulated data sets. The discussed results demonstrate superior performance of the hybrid genetic algorithm in fitting of complex spectra in comparison to the common Monte Carlo method joint with the Powell refinement.
Źródło:
Acta Physica Polonica A; 2005, 108, 1; 95-102
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparative analysis of experimental and theoretical zero-field splitting and Zeeman electronic parameters for Fe²⁺ ions in FeX₂·4H₂O (X = F, Cl, Br, I) and [Fe(H₂O)₆](NH₄)₂(SO₄)₂
Autorzy:
Zając, M.
Rudowicz, C.
Powiązania:
https://bibliotekanauki.pl/articles/1055040.pdf
Data publikacji:
2017-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
33.35.+r
71.70.Ch
71.70.Ej
76.20.+q
76.30.-v
76.30.Fc
87.80.Lg
Opis:
Spectroscopic and magnetic properties of Fe²⁺ (3d⁶; S=2) ions at orthorhombic sites in FeX₂·4H₂O (X = F, Cl, Br, I) crystals are compared with those in [Fe(H₂O)₆](NH₄)₂(SO₄)₂ (FASH). The microscopic spin Hamiltonian modeling utilizing the package MSH/VBA enables prediction of the zero-field splitting parameters and the Zeeman electronic ones. Wide ranges of values of the microscopic parameters, i.e. the spin-orbit (λ), spin-spin (ρ) coupling constants, and the crystal-field (ligand-field) energy levels (Δp_{i}) within the ⁵D multiplet are considered to establish the dependence of the zero-field splitting parameters b_{k}^{q} (in the Stevens notation) and the Zeeman factors g_{i} on λ, ρ, and Δp_{i}. By matching the theoretical spin Hamiltonian parameters and the experimental ones measured by EMR, the suitable values of λ, ρ, and Δp_{i} are determined. The novel aspect is prediction of the fourth-rank zero-field splitting parameters and the ρ (spin-spin)-related contributions, not considered in previous studies. The MSH predictions provide guidance for high-magnetic field and high-frequency EMR measurements.
Źródło:
Acta Physica Polonica A; 2017, 132, 1; 19-23
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dynamics of Light Emission in CdMnS Nanoparticles
Autorzy:
Godlewski, M.
Yatsunenko, S.
Drozdowicz-Tomsia, K.
Goldys, E. M.
Phillips, M. R.
Klar, P. J.
Heimbrodt, W.
Powiązania:
https://bibliotekanauki.pl/articles/2043717.pdf
Data publikacji:
2005-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.07.Wx
78.55.Et
78.47.+p
71.55.Gs
76.30.Fc
76.70.Hb
Opis:
We demonstrate coexistence of slow and fast components of photoluminescence decay of the Mn$\text{}^{2+}$ intra-shell emission in nanoparticles of CdMnS. We explain the observed decrease in PL lifetime of the Mn$\text{}^{2+}$ intra-shell transition by high efficiency of spin dependent magnetic interactions between localized spins of Mn$\text{}^{2+}$ ions and free carriers. This mechanism is enhanced in nanostructures, but it is also present in bulk samples.
Źródło:
Acta Physica Polonica A; 2005, 108, 4; 681-688
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-76 z 76

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