INVESTIGATION OF THE DEFECT STRUCTURE, OPTICAL AND EPR SPECTRA FOR CdS: Ti2+ AND CdSe: Ti2+ CRYSTAL

2009 ◽  
Vol 23 (27) ◽  
pp. 5325-5331 ◽  
Author(s):  
WEN-LIN FENG ◽  
WEN-CHEN ZHENG
Keyword(s):  
Defect Structure ◽  
Spectral Band ◽  
Zero Field ◽  
Spin Orbit ◽  
Defect Structures ◽  
Spin Hamiltonian ◽  
Zero Field Splitting ◽  
Orbit Parameter ◽  
Crystal Field Parameters ◽  
Hamiltonian Parameters

The optical spectral band positions and spin-Hamiltonian parameters (g factors g‖, g⊥ and zero-field splitting D) of CdS : Ti 2+ and CdSe : Ti 2+ crystals are calculated from the complete diagonalizaion (of energy matrix) method based on a two-spin-orbit parameter model for 3d2 ions in trigonal symmetry. In the model, both the contribution to spin-Hamiltonian parameters due to the spin-orbit parameter of central 3d2 ions and that of ligand ions are included. The crystal field parameters used in the calculations are obtained from the superposition model which enables correlation of the optical and EPR spectral data with the defect structure of the studied paramagnetic impurity centers in crystals. From the calculations, the defect structures of Ti 2+ centers in CdS : Ti 2+ and CdSe : Ti 2+ are acquired, the signs of zero-field splittings D are suggested, and the optical band positions and spin-Hamiltonian parameters are explained. The results are discussed.

scholarly journals Investigations of the EPR Parameters and Defect Structures of Two Types of Trigonal Cr3+ Centers in CsMgCl3, CsMgBr3 and CsCdBr3 Crystals

2005 ◽  
Vol 60 (11-12) ◽  
pp. 823-826 ◽  
Author(s):  
Lv He ◽  
Xiao-Xuan Wu ◽  
Wen-Chen Zheng ◽  
Yang Mei
Keyword(s):  
Coupling Parameter ◽  
Zero Field ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Defect Structures ◽  
Zero Field Splitting ◽  
Trigonal Symmetry ◽  
Local Lattice ◽  
Epr Parameters ◽  
Lattice Distortions

The EPR g factors g||, g⊥ and zero-field splitting D of trigonal Cr3+-M+ (M+ = Li+, Cu+, Na+) and Cr3+-VB-M3+ (M3+ = Cr3+, In3+, Sc3+, Y3+, Lu3+; VB denotes the B2+ vacancy) centers in some CsBX3 (B = Mg, Cd; X = Cl, Br) crystals are calculated from high-order perturbation formulas based on the two-spin-orbit coupling parameter model of the 3d3 ion in trigonal symmetry. From the calculations, these EPR parameters are reasonably explained and the local lattice distortions caused by the charge compensators M+ or VB are estimated. The results are discussed.

Studies of the Spin Hamiltonian Parameters for NiX2 and CdX2:Ni2+ (X=Cl, Br)

2009 ◽  
Vol 282 ◽  
pp. 25-30
Author(s):  
Zhi Hong Zhang ◽  
Shao Yi Wu ◽  
Xue Feng Wang ◽  
Yue Xia Hu
Keyword(s):  
Zero Field ◽  
Spin Hamiltonian ◽  
Zero Field Splitting ◽  
Local Structures ◽  
Ligand Orbital ◽  
Distorted Octahedra ◽  
Lattice Distortions ◽  
Hamiltonian Parameters ◽  
Ligand Bond ◽  
G Factors

The spin Hamiltonian parameters (zero-field splitting D and the g factors) for NiX2 and CdX2:Ni2+ (X=Cl, Br) are quantitatively investigated from the perturbation formulas of these parameters for a 3d8 ion in trigonally distorted octahedra based on the cluster approach. In the calculations, the trigonal field parameters  and ′ are determined from the superposition model and the local structures of Ni2+ in the halides. The theoretical g factors show reasonable agreement with the observed values, and the experimental D for CdX2:Ni2+ are also interpreted by considering suitable lattice distortions (angular decreases) in the impurity-ligand bond angles related to the C3 axis due to the size mismatching substitution. The contributions from the ligand orbital and spin-orbit coupling interactions are important and should be taken into account.

scholarly journals Purely Spectroscopic Determination of the Spin Hamiltonian Parameters in High-Spin Six-Coordinated Cobalt(II) Complexes with Large Zero-Field Splitting

2019 ◽  
Vol 58 (24) ◽  
pp. 16434-16444 ◽  
Author(s):  
Eugenii Ya. Misochko ◽  
Alexander V. Akimov ◽  
Denis V. Korchagin ◽  
Joscha Nehrkorn ◽  
Mykhaylo Ozerov ◽  
...  
Keyword(s):  
High Spin ◽  
Spectroscopic Determination ◽  
Zero Field ◽  
Spin Hamiltonian ◽  
Zero Field Splitting ◽  
Field Splitting ◽  
Hamiltonian Parameters

scholarly journals Spin-Hamiltonian Parameters For CrLi3+ Doped In LiNbO3

2012 ◽  
Vol 56 (1) ◽  
pp. 1-8
Author(s):  
N.M. Avram ◽  
M. G. Brik ◽  
C. N. Avram ◽  
M.G. Ciresan ◽  
E-L. Andreici
Keyword(s):  
Coupling Parameter ◽  
Zero Field ◽  
Spin Orbit Coupling ◽  
Spin Hamiltonian ◽  
Cluster Approach ◽  
Zero Field Splitting ◽  
Crystal Field Theory ◽  
State Splitting ◽  
Hamiltonian Parameters ◽  
Good Agreement

AbstractBy using crystal field theory, the spin-Hamiltonian parameters [zero-field splitting D, the giromagnetic factors g (g|| and g⊥) and the first excited state splitting δ(2E)] for the CrLi3+ doped in LiNbO3 have been calculated from the higher-order perturbation formulas. The method used is based on the two-spin-orbit coupling parameter model, in a cluster approach. The g parameters were also calculated as a second derivative of the energy, method implemented into ORCA computer program. The results were discussed and good agreement with experimental data was demonstrated.

Spin-Hamiltonian Parameters of Gd3+ Ion in the Room Temperature Tetragonal Phase of BaTiO3

2014 ◽  
Vol 69 (10-11) ◽  
pp. 606-610 ◽  
Author(s):  
Wei-Qing Yang ◽  
Wen-Chen Zheng
Keyword(s):  
Crystal Field ◽  
Tetragonal Phase ◽  
Structural Data ◽  
Zero Field ◽  
Superposition Model ◽  
Spin Hamiltonian ◽  
Experimental Values ◽  
Crystal Field Parameters ◽  
Hamiltonian Parameters ◽  
Electron Crystal

AbstractThe spin-Hamiltonian parameters (g factors g||, g⊥, and zero-field splittings b02 , b04 , b44 , b06 , b46 ) of the 4f7 Gd3+ ion in the tetragonal phase of a BaTiO3 crystal are calculated through the diagonalization (of energy matrix) method based on the one-electron crystal field mechanism. In the calculations, the crystal field parameters are estimated from the superposition model with the structural data of the studied crystal. It is found that by using three adjustable intrinsic parameters Āk(R0) (k=2, 4, 6) in the superposition model, the seven calculated spin-Hamiltonian parameters are in good agreement with the experimental values, suggesting that the diagonalization method based on one-electron crystal field mechanism is effective in the studies of spin-Hamiltonian parameters for 4f7 ions in crystals.

STUDIES ON THE LOCAL STRUCTURE AND THE SPIN HAMILTONIAN PARAMETERS FOR THE TRIGONAL Mn2+ CENTER IN Bi4Ge3O12

2008 ◽  
Vol 22 (14) ◽  
pp. 1381-1387 ◽  
Author(s):  
XUE-FENG WANG ◽  
SHAO-YI WU ◽  
ZHI-HONG ZHANG ◽  
LI-HUA WEI ◽  
YUE-XIA HUA
Keyword(s):  
Hyperfine Structure ◽  
Local Structure ◽  
Zero Field ◽  
Spin Hamiltonian ◽  
Zero Field Splitting ◽  
Trigonal Symmetry ◽  
Oxygen Octahedron ◽  
Structure Constants ◽  
Hamiltonian Parameters ◽  
Good Agreement

The local structure and the spin Hamiltonian parameters (the zero-field splitting D, the g factors g//, g⊥ and the hyperfine structure constants A// and A⊥) for the trigonal Mn 2+ center in Bi 4 Ge 3 O 12 are theoretically studied from the perturbation formulas of these parameters for a 3d5 ion in trigonal symmetry. The impurity Mn 2+ replacing host Bi 3+ is not found to occupy the exact Bi 3+ site but to suffer a large off-center displacement by about 0.36 Å towards the center of the oxygen octahedron along the C3-axis due to the size and charge mismatching substitution. The calculated spin Hamiltonian parameters based on the above displacement show good agreement with the observed values. The results and the mechanism of the impurity displacement are discussed.

Studies of the Axial Shift and the Spin Hamiltonian Parameters for Mn2+ in a CdS Crystal

2009 ◽  
Vol 294 ◽  
pp. 77-83
Author(s):  
Xue Feng Wang ◽  
Shao Yi Wu ◽  
Yue Xia Hu ◽  
Pei Xu
Keyword(s):  
Reasonable Agreement ◽  
Zero Field ◽  
Spin Orbit Coupling ◽  
Spin Hamiltonian ◽  
Cluster Approach ◽  
Zero Field Splitting ◽  
Ligand Orbital ◽  
Axial Shift ◽  
Structure Constants ◽  
Hamiltonian Parameters

The axial shift and the spin Hamiltonian parameters (zero-field splitting D, the g factors and the hyperfine structure constants A// and A) for Mn2+ in a CdS crystal are studied theoretically in this work. The calculations are carried out by using the perturbation formulae of these parameters for a 3d5 ion under trigonally distorted tetrahedra based upon the cluster approach, where the ligand orbital and spin-orbit coupling contributions are taken into account in a uniform way. From the studies, the impurity Mn2+ is found not to occupy the host Cd2+ site exactly but to experience a small outward shift of 0.018 Å away from the ligand triangle along the C3 axis. The above impurity axial shift leads to a much smaller trigonal distortion than the host Cd2+ site in CdS. The calculated spin Hamiltonian parameters are in reasonable agreement with the experimental data.

scholarly journals Spin–spin interactions in defects in solids from mixed all-electron and pseudopotential first-principles calculations

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Krishnendu Ghosh ◽  
He Ma ◽  
Mykyta Onizhuk ◽  
Vikram Gavini ◽  
Giulia Galli
Keyword(s):  
First Principles ◽  
Quantum Dynamics ◽  
Density Functional ◽  
Spin Interaction ◽  
Zero Field ◽  
First Principles Calculations ◽  
Spin Hamiltonian ◽  
Zero Field Splitting ◽  
Electron Level ◽  
Hamiltonian Parameters

AbstractUnderstanding the quantum dynamics of spin defects and their coherence properties requires an accurate modeling of spin-spin interaction in solids and molecules, for example by using spin Hamiltonians with parameters obtained from first principles calculations. We present a real-space approach based on density functional theory for the calculation of spin-Hamiltonian parameters, where only selected atoms are treated at the all-electron level, while the rest of the system is described with the pseudopotential approximation. Our approach permits calculations for systems containing more than 1000 atoms, as demonstrated for defects in diamond and silicon carbide. We show that only a small number of atoms surrounding the defect needs to be treated at the all-electron level, in order to obtain an overall all-electron accuracy for hyperfine and zero-field splitting tensors. We also present results for coherence times, computed with the cluster correlation expansion method, highlighting the importance of accurate spin-Hamiltonian parameters for quantitative predictions of spin dynamics.

ESR SPECTRUM OF Fe+3 IN TOPAZ: I. FINE STRUCTURE

1967 ◽  
Vol 45 (11) ◽  
pp. 3597-3610 ◽  
Author(s):  
J. R. Thyer ◽  
S. M. Quick ◽  
F. Holuj
Keyword(s):  
Fine Structure ◽  
Zero Field ◽  
Spin Hamiltonian ◽  
Zero Field Splitting ◽  
Field Splitting ◽  
Esr Spectrum ◽  
Hamiltonian Parameters ◽  
Near Future ◽  
K Band

ESR spectrum of Fe+3 in topaz (Al2SiO4F2) has been investigated at X- and K-band frequencies. The spectrum, in addition to large zero-field splitting, also shows well-resolved h.f.s. due to 19F at some orientations. The spin-Hamiltonian parameters, which include b21 and b41, are given in the text. The spectrum has been interpreted to originate from Fe+3 impurity located at Al+3 sites. The implications of these results are considered briefly. The results of the analysis of the h.f.s. are to be published in the near future.

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