The Experts below are selected from a list of 213 Experts worldwide ranked by ideXlab platform
Wen-chen Zheng - One of the best experts on this subject based on the ideXlab platform.
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Spin-Hamiltonian Parameters of Gd3+ Ion in the Room Temperature Tetragonal Phase of BaTiO3
Zeitschrift für Naturforschung A, 2014Co-Authors: Weiqing Yang, Wen-chen ZhengAbstract:Abstract The 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.
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Investigations of the Spin-Hamiltonian Parameters for the Rhombic Mo5+ Centers in Ca1−xYxMoO4 Crystal
Applied Magnetic Resonance, 2014Co-Authors: Ren-ming Peng, Wen-chen ZhengAbstract:The Spin-Hamiltonian parameters (g factors g i and hyperfine structure constants A i , where i = x, y, z) of the rhombic Mo5+ center in Ca1−x Y x MoO4 crystal are calculated from the high-order perturbation formulas based on the two-mechanism model for the rhombic d1 tetrahedral clusters with the ground state |d z 2〉. In these formulas, besides the contributions due to the widely applied crystal-field (CF) mechanism concerning CF excited states, those due to the charge-transfer (CT) mechanism (which is omitted in CF theory) concerning CT excited states are considered. The calculated results are in reasonable agreement with the experimental values. The calculations show that because of the great relative importance of CT mechanism for the components of Spin-Hamiltonian parameter along x and y axes, the accurate and complete calculations of Spin-Hamiltonian parameters for Mo5+ and other high valence state dn ions in crystals should take account of both the CF and CT mechanisms. The defect model of the rhombic Mo5+ center is also confirmed from the calculations.
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theoretical analysis of Spin Hamiltonian parameters for the rhombic cu2 centres in cugase2 crystals
Molecular Physics, 2014Co-Authors: Wenlin Feng, Wen-chen ZhengAbstract:The Spin-Hamiltonian parameters (g factors gi and hyperfine structure constants Ai, where i = x, y, z) of the rhombic Cu2+ centres in the CuGaSe2 crystal are determined from the high-order perturbation formulae based on the cluster approach (sometimes also called two-Spin-orbit parameter model). In the studies, some parameters in the analysis of g factors for the same centre within the tetragonal symmetry approximation in the previous paper are used, and the parameter due to the perturbation of rhombic crystal field caused by a charge compensator at, e.g., [110] direction are considered. As the result of a fitting process, the determined Spin-Hamiltonian parameters are in reasonable agreement with the experimental values. The results are discussed.
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Research on the Spin-Hamiltonian parameters and defect structure for Ni+ ion in CdS
Physica B-condensed Matter, 2013Co-Authors: Wen-chen Zheng, Lv He, Wei LiAbstract:The Spin-Hamiltonian parameters (g factors gu(//), g(perpendicular to) and hyperfine structure constants A(//), A(perpendicular to)) for Ni+ in the trigonally-distorted tetrahedral Cd2+ site of CdS are calculated from the complete diagonalization (of energy matrix) method with the suitable parameters. In the method, the contributions to Spin-Hamiltonian parameters from both the Spin-orbit parameters of central d(n) ion and ligands are contained and the interactions among all the ground and excited states are considered. The calculated results show reasonable agreement with the experimental values. The defect structure of Ni+ center, which is similar to those of other 3d(n) centers in CdS, is obtained from the calculation. (C) 2012 Elsevier B.V. All rights reserved.
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Spin Hamiltonian parameters for the tetragonal gd m 3 f i centers in caf2 and srf2 crystals
Journal of Magnetic Resonance, 2013Co-Authors: Weiqing Yang, Wen-chen Zheng, Ying ZhangAbstract:Abstract The Spin-Hamiltonian parameters ( g factors g // , g ⊥ and zero-field splittings b 2 0 , b 4 0 , b 4 4 , b 6 0 , b 6 4 ) of the tetragonal Gd M 3 + – F i - centers in CaF 2 and SrF 2 crystals at T ≈ 1.8 K are calculated from the diagonalization (of energy matrix) method based on the one-electron crystal field mechanism. In the calculations, the crystal field parameters used are estimated from the superposition model with the reported defect structural data obtained from the analyses of superhyperfire interaction constants at the same temperature. The calculated results are in reasonable agreement with the experimental values. It appears that the above defect structural data reported in the previous paper are suitable and the diagonalization (of energy matrix) method is effective to the studies of Spin-Hamiltonian parameters for 4 f 7 ions in crystals.
Weiqing Yang - One of the best experts on this subject based on the ideXlab platform.
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Spin-Hamiltonian Parameters of Gd3+ Ion in the Room Temperature Tetragonal Phase of BaTiO3
Zeitschrift für Naturforschung A, 2014Co-Authors: Weiqing Yang, Wen-chen ZhengAbstract:Abstract The 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.
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Spin Hamiltonian parameters for the tetragonal gd m 3 f i centers in caf2 and srf2 crystals
Journal of Magnetic Resonance, 2013Co-Authors: Weiqing Yang, Wen-chen Zheng, Ying ZhangAbstract:Abstract The Spin-Hamiltonian parameters ( g factors g // , g ⊥ and zero-field splittings b 2 0 , b 4 0 , b 4 4 , b 6 0 , b 6 4 ) of the tetragonal Gd M 3 + – F i - centers in CaF 2 and SrF 2 crystals at T ≈ 1.8 K are calculated from the diagonalization (of energy matrix) method based on the one-electron crystal field mechanism. In the calculations, the crystal field parameters used are estimated from the superposition model with the reported defect structural data obtained from the analyses of superhyperfire interaction constants at the same temperature. The calculated results are in reasonable agreement with the experimental values. It appears that the above defect structural data reported in the previous paper are suitable and the diagonalization (of energy matrix) method is effective to the studies of Spin-Hamiltonian parameters for 4 f 7 ions in crystals.
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Investigations of the Spin-Hamiltonian parameters for Yb3+in the tetragonal phase of SrTiO3 crystal
Philosophical Magazine, 2010Co-Authors: Wen-chen Zheng, Weiqing Yang, Bang-xing LiAbstract:The Spin-Hamiltonian parameters (g factors, , , and hyperfine structure constants, , ) for Yb3+ at the 12-fold coordinated Sr2+ site of tetragonal SrTiO3 crystal at T ≈ 2 and 50 K were calculated using the completed diagonalization (of the energy matrix) method (CDM). Differing from the conventional CDM, the Hamiltonian concerning the energy matrix in this CDM contains the Zeeman and hyperfine interaction terms and so the Spin-Hamiltonian parameters can be calculated directly from CDM. The crystal parameters used in the energy matrix are calculated from the superposition model, in which the tetragonal distortions and hence the order parameters φ at both temperatures are applied. From the calculations, the Spin-Hamiltonian parameters at both temperatures are explained reasonably and the signs of hyperfine structure constants for the 171Yb3+ and 173Yb3+ isotopes in SrTiO3 are suggested. The results are discussed.
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Investigation of the Spin-Hamiltonian parameters for the trigonal U5+ center in CaF2 crystal
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2010Co-Authors: Wen-chen Zheng, Weiqing Yang, Ping SuAbstract:Abstract The Spin-Hamiltonian parameters (g factor g//, g⊥ and hyperfine structure constants A//, A⊥) of the trigonal U5+ center in CaF2 crystal have been calculated from the complete diagonalization (of energy matrix) method (CDM) for 5f1 ions in trigonal crystal field and under an external magnetic field. In the calculation, the crystal-field parameters are estimated from the superposition model. From the calculations, these Spin-Hamiltonian parameters are reasonably explained, and the defect model (i.e., the trigonal U5+ center is attributed to U5+ substituting for Ca2+ in CaF2 with six F− ions replaced by O2− and the other two F− sites vacant because of charge compensation) given in the previous paper is confirmed. The results are discussed.
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Investigations of the Spin-Hamiltonian parameters for Er3+ions in AlN crystal
Molecular Physics, 2009Co-Authors: Gui-qiang Qu, Wen-chen Zheng, Weiqing YangAbstract:The Spin-Hamiltonian parameters (g factor g //, g ⊥ and hyperfine structure constants A //, A ⊥) for Er3+ ion at the trigonal Al3+ site of AlN crystal are calculated by diagonalising the 52 × 52 energy matrix. The matrix are related to the ground mutiplet 4I15/2 and the first to third excited multiplets 4I13/2, 4I11/2 and 4I9/2 for 4f11 ions in trigonal crystal field under an external magnetic field. The crystal-field parameters used in the matrix are obtained from the superposition model and the local lattice relaxation due to the substitution of Er3+ for Al3+ is considered. The calculated Spin-Hamiltonian parameters are in reasonable agreement with the experimental values and the signs of hyperfine structure constants are suggested. The results are discussed.
Shao-yi Wu - One of the best experts on this subject based on the ideXlab platform.
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Studies of the Spin Hamiltonian parameters and defect structures for Ag2+ in NaF and CsCdF3 crystals
Physica B-condensed Matter, 2016Co-Authors: Li-juan Zhang, Shao-yi Wu, Chang-chun Ding, Xian-fen Hu, Jia-jun HeAbstract:The Spin Hamiltonian parameters (g factors g//, g⊥, hyperfine structure constants A//, A⊥ and superhyperfine parameters Az′, Ax′ and Ay′) and defect structures for Ag2+ in NaF and CsCdF3 crystals are theoretically studied using the improved perturbation formulas of these quantities for a 4d9 ion in a tetragonally elongated octahedron. The contributions from both the crystal-field and charge transfer mechanisms are taken into account, and the relevant model parameters are quantitatively obtained from the cluster approach in a consistent way. The impurity centers are found to undergo the relative tetragonal elongations of about 9.4% and 8.2% for Ag2+ in NaF and CsCdF3, respectively, along the C4 axis due to the Jahn–Teller effect. By employing the few adjustable parameters, the calculated Spin Hamiltonian parameters based on the above uniform formulas and the local tetragonal elongation distortions agree well with the experimental data. Despite dominant ionicity of the hosts, the charge transfer contributions are actually important to the Spin Hamiltonian parameters (e.g., about 20% for the g-shifts) due to strong covalency of impurity Ag2+.
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INVESTIGATIONS ON THE Spin Hamiltonian PARAMETERS FOR Cu 2+ IN NaCl AND AgCl
Journal of Applied Spectroscopy, 2015Co-Authors: Y. K. Cheng, Shao-yi Wu, Chang-chun Ding, Min-quan KuangAbstract:The Spin Hamiltonian parameters (g factors and hyperfine structure constants) for Cu2+ in NaCl and AgCl are investigated theoretically for the case of the 3d 9 ion in tetragonally elongated octahedra using high-order perturbation formulas for these parameters. Due to the Jahn–Teller effect, the impurity Cu2+ centers are found to experience relative elongations along the four-fold axis of about 0.15 and 0.08 A in NaCl and AgCl, respectively. The calculated Spin Hamiltonian parameters are in good agreement with the experimental data. The local structures and EPR spectra of the systems are discussed.
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Theoretical investigations of the local structure and the Spin Hamiltonian parameters for Ti2+ in MgCl2
Physica B-condensed Matter, 2013Co-Authors: Zhi-hong Zhang, Shao-yi Wu, Xian-fen Hu, Min-quan KuangAbstract:Abstract The local structure and Spin Hamiltonian parameters (zero-field splitting and g factors) for Ti2+ in MgCl2 are theoretically studied using the perturbation formulas of these parameters for a 3d2 ion under trigonally distorted octahedra. The contributions from the dynamical Jahn–Teller effect, the configuration interactions and the ligand orbital and Spin–orbit coupling interactions are quantitatively involved based on the cluster approach in a uniform way. The chlorine polyhedron around the impurity Ti2+ is found to transform from a slightly compressed octahedron in pure MgCl2 to a slightly elongated one, characterized by the local angular decrease of 0.3° related to the host bond angle 54.78° due to the Jahn–Teller effect. The calculated Spin Hamiltonian parameters based on the above trigonal elongation show good agreement with the experimental data. The results are discussed.
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Studies on the axial shift and the Spin Hamiltonian parameters for Cr + in BeO
European Physical Journal-applied Physics, 2013Co-Authors: Bo-tao Song, Shao-yi Wu, Min-quan Kuang, Zhi-hong ZhangAbstract:The axial shift and the Spin Hamiltonian parameters (zero-field splitting D , g factors and hyperfine structure constants) for Cr + in BeO are theoretically studied in this work. The calculations are carried out by using the perturbation formulas of these parameters for a 3 d 5 ion under trigonally distorted tetrahedra based on the cluster approach containing both the crystal-field and charge transfer contributions. It is found that the impurity Cr + may not occupy exactly the host Be 2+ site but experience a small outward shift 0.01 A away from the ligand triangle along the C 3 axis. The above impurity axial shift leads to much smaller trigonal distortion than the host Be 2+ site in BeO. The theoretical Spin Hamiltonian parameters based on the above impurity axial shift are in good agreement with the observed values.
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theoretical studies on the local structure and Spin Hamiltonian parameters for the orthorhombic cu2 center in linbo3
Optik, 2012Co-Authors: Min-quan Kuang, Shao-yi Wu, Hua-ming ZhangAbstract:The local structure and Spin Hamiltonian parameters (the g factors and the hyperfine structure constants) for the orthorhombic Cu2+ center in LiNbO3 are theoretically studied from the perturbation formulas of these parameters for a 3d(9) ion in an orthorhombically elongated octahedron. This center is ascribed to Cu2+ occupying the Nb5+ site in LiNbO3, associated with one nearest neighbour oxygen vacancy V-O along the Z axis. The planar bond lengths are found to suffer the relative variation of about 0.16 angstrom by compressing and stretching the Cu2+-O2- bonds along the X and Y axes, respectively, due to the Jahn-Teller effect and the charge mismatching substitution of Nb5+ by Cu2+. Meanwhile, the effectively positive V-O can make the central Cu2+ displace away from the V-O along the Z axis by about 0.3 angstrom. The theoretical Spin Hamiltonian parameters based on the above local distortions show good agreement with the experimental data. (C) 2011 Elsevier GmbH. All rights reserved.
Kazuki Iida - One of the best experts on this subject based on the ideXlab platform.
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determination of Spin Hamiltonian in the ni4 magnetic molecule
Physical Review B, 2012Co-Authors: Kazuki Iida, Takahiro Onimaru, Kazuyuki Matsubayashi, Toshihiro SatoAbstract:Magnetic excitations in a Ni${}_{4}$ magnetic molecule were investigated by inelastic neutron scattering and bulk susceptibility (${\ensuremath{\chi}}_{\mathrm{bulk}}$) techniques. The magnetic excitation spectrum obtained from the inelastic neutron scattering experiments exhibits three modes at energy transfers of $\ensuremath{\hbar}\ensuremath{\omega}=0.5$, 1.35, and 1.6 meV. We show that the energy, momentum, and temperature dependencies of the inelastic neutron scattering data and ${\ensuremath{\chi}}_{\mathrm{bulk}}$ can be well reproduced by an effective Spin Hamiltonian consisting of intramolecule exchange interactions, a single-ionic anisotropy, biquadratic interactions, and a Zeeman term. Under hydrostatic pressure, the bulk magnetization decreases with increasing pressure, which along with the biquadratic term indicates Spin-lattice coupling present in this system.
S M Aldoshin - One of the best experts on this subject based on the ideXlab platform.
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purely spectroscopic determination of the Spin Hamiltonian parameters in high Spin six coordinated cobalt ii complexes with large zero field splitting
Inorganic Chemistry, 2019Co-Authors: Eugenii Ya Misochko, Alexander V Akimov, D V Korchagin, Joscha Nehrkorn, M Ozerov, Andrew Palii, Juan M Clementejuan, S M AldoshinAbstract:Accurate determination of the Spin Hamiltonian parameters in transition-metal complexes with large zero-field splitting (ZFS) is an actual challenge in studying magnetic and spectroscopic properties of high-Spin transition metal complexes. Recent critical papers have convincingly shown that previous determinations of these parameters, based only on the magnetic data, have low accuracy and reliability. A combination of X-band electron paramagnetic resonance (EPR) spectroscopy and SQUID magnetometry seems to be a more convincing and accurate approach. However, even in this case, the accuracy of the determination of the Spin Hamiltonian parameters is strongly limited. In this work, we propose a purely spectroscopic approach, in which three complementary EPR spectroscopic techniques are used to unambiguously with high accuracy determine the Spin Hamiltonian parameters for transition-metal complexes with S = 3/2. The applicability of this approach is demonstrated by analyzing the new quasi-octahedral high-Spin...
