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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

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