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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:
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:
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:
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:
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:
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:
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:
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:
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:
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:
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:
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 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:
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:
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

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