THEORETICAL STUDIES ON THE GYROMAGNETIC FACTORS FORFe3+INZnX(X=O,S,Se,Te)

2010 ◽  
Vol 24 (17) ◽  
pp. 1891-1898 ◽  
Author(s):  
XUE-FENG WANG ◽  
SHAO-YI WU ◽  
PEI XU ◽  
LI-LI LI
Keyword(s):  
Experimental Data ◽  
Charge Transfer ◽  
Crystal Field ◽  
Reasonable Agreement ◽  
Model Parameters ◽  
Theoretical Studies ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Cluster Approach ◽  
Perturbation Formula

The gyromagnetic factors for Fe3+in ZnX ( X = O , S , Se , Te ) are theoretically studied from the perturbation formula of the g-factor for a 3d5ion in tetrahedra based on inclusion of both the crystal-field and the charge-transfer contributions. The related model parameters in the calculations are determined from the cluster approach in a uniform way. The g-shift Δg (= g-gs, where gs≈ 2.0023 is the spin-only value) from the charge-transfer contributions is opposite (positive) in sign and much larger in magnitude as compared with that from the crystal-field ones. The importance of the charge-transfer contributions increases rapidly with increasing the covalency and the spin-orbit coupling coefficient of the ligand and thus exhibits the order of O2-< S2-< Se2-< Te2-. The calculated g-factors by considering both the crystal-field and charge-transfer contributions show reasonable agreement with the experimental data for all the Fe3+centers in ZnX .

Theoretical studies of the anisotropic g factors for deoxygenated Y123

2015 ◽  
Vol 29 (25n26) ◽  
pp. 1542017
Author(s):  
L. J. Zhang ◽  
S. Y. Wu ◽  
C. C. Ding ◽  
Y. K. Cheng
Keyword(s):  
Experimental Data ◽  
Orbit Coupling ◽  
Theoretical Studies ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Cluster Approach ◽  
Ligand Orbital ◽  
Y123 System ◽  
Good Agreement ◽  
G Factors

The anisotropic [Formula: see text] factors of the deoxygenated YBaCuO (Y123) are theoretically studied using the perturbation formulas of the [Formula: see text] factors for a tetragonally elongated octahedral [Formula: see text] cluster. The ligand orbital and spin-orbit coupling contributions are included from the cluster approach in view of covalency. The calculated [Formula: see text] factors show good agreement with the experimental data. The anisotropy of the [Formula: see text] factors is analyzed by considering the local tetragonal elongation distortion around this five-fold coordinated [Formula: see text] site in the deoxygenated Y123 system.

Study on the Absorption Spectra of Ga2Se3:Co2+ Single Crystals

2009 ◽  
Vol 64 (12) ◽  
pp. 834-836
Author(s):  
Chao Ni ◽  
Yi Huang ◽  
Maolu Du
Keyword(s):  
Experimental Data ◽  
Fine Structure ◽  
Bond Length ◽  
Single Crystals ◽  
Crystal Field ◽  
Energy Levels ◽  
Crystal Field Parameter ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Cubic Crystal

Introducing the average covalent factor N and considering the interaction of the cubic crystal field, the spin-orbit coupling and Tree’s correction effects, the crystal field parameter Dq was calculated. Also the varying tendency of Dq with the bond length R was investigated. Using the complete diagonalizing method the energy levels of the fine structure of Ga2Se3:Co2+ single crystal were calculated and assigned. The calculated and assigned results are consistent with the experimental data

Investigation of the multiplet structures and crystal field effects of a TiO6 3d 1 cluster based on configuration interaction calculations

2017 ◽  
Vol 50 (2) ◽  
pp. 576-584 ◽  
Author(s):  
Meng Wu ◽  
Jin-Cheng Zheng ◽  
Hui-Qiong Wang
Keyword(s):  
Charge Transfer ◽  
Crystal Field ◽  
Configuration Interaction ◽  
Local Density ◽  
Orbit Coupling ◽  
Crystal Field Splitting ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Transfer Energy ◽  
Field Splitting

Configuration interaction cluster calculation can effectively reproduce the experimentally measured Ti L 23-edge absorption spectrum for the TiO6 cluster LaTiO3. A further investigation of the hybridization strength and charge-transfer energy effects on the multiplet structures suggests that LaTiO3 should be classified as an intermediate state between the charge-transfer and Mott–Hubbard regimes. Detailed temperature-dependent simulations of absorption spectra support the lifting of Ti t 2g orbital degeneracy and crystal field splitting. The spin–orbit coupling scenario is ruled out, even though 3d spin–orbit coupling can reproduce the experimental spectrum without including temperature. A combined polarization- and crystal-field-splitting-dependent analysis indicates asymmetric ΔCF–orbital interactions for the TiO6 cluster [Ti3+:3d 1(t 2g 1)], different from the orbital–lattice interactions reported for the NiO6 cluster [Ni3+:3d 7(t 2g 6 eg 1)]. The orbital polarization is defined in terms of the normalized electron occupancies in orbitals with xy and xz(yz) symmetries, and nearly complete orbital polarization (more than 75%) is observed, indicating strongly reduced orbital fluctuations due to the correlation effects. This is consistent with the density of states for titanates based on local density approximation plus dynamical mean-field theory calculations.

Investigations Of The G Factors Of Fe+ In Mgo And Cao

2005 ◽  
Vol 60 (5) ◽  
pp. 366-368 ◽  
Author(s):  
Shao-Yi Wu ◽  
Hui-Ning Dong
Keyword(s):  
Orbit Coupling ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Octahedral Symmetry ◽  
Cluster Approach ◽  
Coupling Interaction ◽  
Perturbation Formula ◽  
Jahn Teller ◽  
Jahn Teller Effect ◽  
G Factors

The g factors of Fe+ in MgO and CaO are theoretically investigated by the perturbation formula of the g factor of a 3d7 ion in cubic octahedral symmetry based on the cluster approach. By considering the partial quenching of the spin-orbit coupling interaction and the effective Land´e factor due to the dynamic Jahn-Teller effect (DJTE), the experimental g factors of the studied systems are reasonably interpreted. It can be suggested that the small g factors of the Fe+ centers in MgO and CaO can be likely attributed to the DJTE, rather than the covalency effect within the scheme of the static crystalfield model.

INVESTIGATIONS ON THE LOCAL STRUCTURE AND THE EPR PARAMETERS FORCu2+-DOPEDGaN

2008 ◽  
Vol 22 (18) ◽  
pp. 1739-1747 ◽  
Author(s):  
LI-HUA WEI ◽  
SHAO-YI WU ◽  
ZHI-HONG ZHANG ◽  
HUI WANG ◽  
XUE-FENG WANG
Keyword(s):  
Experimental Data ◽  
Local Structure ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Cluster Approach ◽  
Ligand Orbital ◽  
Epr Parameters ◽  
Structure Constants ◽  
Slight Displacement ◽  
Good Agreement

The local structure and the EPR parameters (g factors and the hyperfine structure constants) for Cu2+in GaN are theoretically studied from the perturbation formulas of these parameters for a 3d9ion in trigonally distorted tetrahedra. In these formulas, the ligand orbital and spin-orbit coupling contributions are taken into account from the cluster approach, in view of the strong covalency effect of the system. Based on the studies, the impurity Cu2+is found not to occupy exactly the host Ga3+site but to suffer a slight displacement (≈ 0.004 Å ) towards the ligand triangle along C3axis due to charge and size mismatching substitution. The theoretical EPR parameters show good agreement with the experimental data. The validity of the impurity displacement is also discussed.

Investigations of the Isotropic G Factors for the Cubic Fe+ Centers in LiF and NaF

2013 ◽  
Vol 634-638 ◽  
pp. 91-94
Author(s):  
Xian Fen Hu ◽  
Shao Yi Wu ◽  
Min Quan Kuang ◽  
Bo Tao Song
Keyword(s):  
Crystal Field ◽  
Orbit Coupling ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Cubic Crystal ◽  
G Factor ◽  
Perturbation Formula ◽  
Ligand Orbital ◽  
G Factors

The g factors for the cubic Fe+centers in LiF and NaF are theoretically investigated from the perturbation formula of the g factor for an octahedral 3d7cluster including the contributions from the ligand orbital and spin-orbit coupling interactions. The increasing order of the g factor (i.e., LiF < NaF) can be ascribed to the decrease in covalency and the strength of cubic crystal-field of the systems. The validity of the results is discussed.

Studies of the g Factors and the Hyperfine Structure Constants for the Octahedral Interstitial Mn2+ and Cr+ Impurities in Silicon

2013 ◽  
Vol 68 (5) ◽  
pp. 337-342 ◽  
Author(s):  
Bo-Tao Song ◽  
Shao-Yi Wu ◽  
Zhi-Hong Zhang ◽  
Li-Li Li
Keyword(s):  
Experimental Data ◽  
Charge Transfer ◽  
Hyperfine Structure ◽  
Crystal Field ◽  
Structure Constant ◽  
Cluster Approach ◽  
Hyperfine Structure Constant ◽  
Structure Constants ◽  
Good Agreement ◽  
G Factors

The g factors and the hyperfine structure constants for the octahedral interstitial Mn2+ and Cr+ impurities in silicon are theoretically studied using the perturbation formulas of these parameters for an octahedral 3d5 cluster. In the calculations, both the crystal-field and charge transfer contributions are taken into account in a uniform way, and the related molecular orbital coefficients are quantitatively determined from the cluster approach. The theoretical g factors and the hyperfine structure constants are in good agreement with the experimental data. The charge transfer contribution to the g-shift (≈g-gs, where gs ≈ 2:0023 is the spin only value) is opposite (positive) in sign and about 51% - 116% in magnitude as compared with the crystal-field one for Mn2+ and Cr+, respectively. Nevertheless, the charge transfer contribution to the hyperfine structure constant has the same sign and about 12% - 19% that of the crystal-field one. Importance of the charge transfer contribution shows the order Cr+ < Mn2+ due to increase of the impurity valence state in the same host, especially for the g factor.

Investigation of the Spin Hamiltonian Parameters of a Tetragonal VO2+ Center in (NH4)2SbCl5

2006 ◽  
Vol 61 (10-11) ◽  
pp. 583-587 ◽  
Author(s):  
Ji-Zi Lin ◽  
Shao-Yi Wu ◽  
Qiang Fu ◽  
Guang-Duo Lu
Keyword(s):  
Experimental Data ◽  
Hyperfine Structure ◽  
Coupling Coefficient ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Spin Hamiltonian ◽  
Cluster Approach ◽  
Crystal Fields ◽  
Structure Constants ◽  
Hamiltonian Parameters

The spin Hamiltonian parameters g‖ and g⊥ and the hyperfine structure constants A‖ and A⊥ of a tetragonal VO2+ center in (NH4)2SbCl5 are investigated, using the perturbation formulas for a 3d1 ion in tetragonally compressed octahedra. In these formulas, the contributions to the spin Hamiltonian parameters from the s- and p-orbitals as well as the spin-orbit coupling coefficient of the Cl− ligand are taken into account, based on the cluster approach. According to these studies, compression of the ligand octahedra results from the strong axial crystal-fields due to the short V4+-O2− bond in the [VOCl4]2− cluster. The obtained spin Hamiltonian parameters agree well with the experimental data and need fewer adjustable parameters than the previous studies. The covalency of the studied system is also discussed.

Investigations on the EPR Parameters for the Square Planar Cu2+ Centers in K2PdX4 (X = Cl, Br)

2009 ◽  
Vol 64 (5-6) ◽  
pp. 387-392 ◽  
Author(s):  
Chuan-Ji Fu ◽  
Shao-Yi Wu ◽  
Yue-Xia Hu ◽  
Xue-Feng Wang ◽  
Wang-He Wei
Keyword(s):  
Charge Transfer ◽  
Reasonable Agreement ◽  
Adjustable Parameter ◽  
Spin Orbit Coupling ◽  
Superposition Model ◽  
Cluster Approach ◽  
Local Structures ◽  
Square Planar ◽  
Epr Parameters ◽  
Structure Constants

The EPR parameters g factors g||, g⊥ and the hyperfine structure constants A|| and A⊥ for the square planar Cu2+ centers in K2-PdX4 (X = Cl, Br) are theoretically investigated from the perturbation formulas of these parameters for a 3d9 ion under tetragonally elongated octahedra. In these formulas, not only the contributions from the conventional crystal-field (CF) mechanism, but also those from the charge-transfer (CT) mechanism are taken into account. The related molecular orbital coefficients are uniformly determined from the cluster approach, and the tetragonal field parameters Ds and Dt are obtained from the superposition model and the local structures of the systems. Based on only one adjustable parameter, the present results are in reasonable agreement with the observed values. Importance of the charge-transfer contributions is more significant for ligand Br than that for Cl due to the stronger covalency and much larger spin-orbit coupling coefficient of the former.

The suppression of spin–orbit coupling effect by the ZnO layer of La0.7Sr0.3MnO3/ZnO heterostructures grown on (001) oriented Si restores the negative magnetoresistance

Nanoscale ◽  
2021 ◽  
Author(s):  
Bibekananda Das ◽  
Prahallad Padhan
Keyword(s):  
Charge Transfer ◽  
Coupling Effect ◽  
Orbit Coupling ◽  
Negative Magnetoresistance ◽  
Magnetic Scattering ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Interfacial Charge Transfer ◽  
Positive Magnetoresistance ◽  
Interfacial Charge

In Si–La0.7Sr0.3MnO3, the interfacial charge transfer driven strong localized antiferromagnetic and spin–orbit couplings favor positive magnetoresistance, which is suppressed by strong magnetic scattering induced by the top ZnO layer results in negative magnetoresistance.

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