掺杂晶体材料ZnGa_2O_4:Fe^(3+)局域结构畸变及其微观自旋哈密顿参量研究  

Local structure distortion and the spin-Hamiltonian parameters for Fe^(3+)-doped ZnGa_2O_4 crystal materials

作　　者：杨子元[1] 

机构地区：[1]宝鸡文理学院物理与信息技术系,宝鸡721013

出　　处：《物理学报》2014年第17期289-297,共9页Acta Physica Sinica

基　　金：陕西省教育厅自然科学专项基金(批准号:11JK0537)资助的课题~~

摘　　要：基于Newman的晶场叠模型与微观自旋哈密顿理论,建立了ZnGa2O4:Fe3+晶体材料中磁性离子Fe3+局域结构与其自旋哈密顿(spin-Hamiltonian,SH)参量(包括二阶零场分裂(zero-field splitting,ZFS)参量D,四阶ZFS参量(a-F),Zeeman g因子:g//,g⊥,△g(=g//-g⊥))之间的定量关系.采用以全组态完全对角化方法为理论背景的CFA/MSH(Crystal Filed Analysis/Microscopic Spin Hamiltonian)研究软件,研究了ZnGa2O4:Fe3+材料中磁性离子Fe3+的SH参量与其局域结构的依赖关系.研究表明:对于ZnGa2O4:Fe3+晶体材料,当磁性离子Fe3+的局域结构畸变参数△R=0.0487 nm,△θ=0.192°时,其基态SH参量理论计算结果与实验测量符合很好,进一步表明Fe3+掺入晶体材料后将引起磁性Fe3+离子局域结构的微小畸变,但其仍然保持D3d点群对称局域结构.在此基础上研究分析了SH参量的微观起源,结果表明:ZnGa2O4:Fe3+晶体材料的SH参量主要来源于SO(spin-orbit)磁相互作用机理,来自其他磁相互作用机理(包括SS(spin-spin),SOO(spin-other-orbit),OO(orbit-orbit),SO-SS-SOO-OO)的贡献比较小.Relations between the spin-Hamiltonian （SH） parameters including the second-order zero-field splitting （ZFS） parameter D,the fourth-order ZFS parameter Ca-F）, the Zeeman g-factors： g//, g⊥, △g（= g// - g⊥） and the structural parameters of ZnGa2O4：Fe3＋ crystals have been established by means of the microscopic spin Hamiltonian theory and Newman＇s crystal field （CF） superposition model. On the basis of this, the SH parameters for Fe3＋ magnetic ions in ZnGa2O4：Fe3＋ crystals are investigated theoretically using the CFA/MSH （crystal field analysis/microscopic spin- Hamiltonian） software based on the full configuration complete diagonalization method. It is found that the theoretically calculated parameters including the ZFS parameters D, （a-F）, and the Zeeman g-factors： g//, ⊥g, △g（= g//-g⊥） for ZnGa2O4：Fe3＋ crystals are in good agreement with experimental data when taking into account the lattice distortions： △R = 0.0487 nm and △θ = 0.192°. This investigation reveals that there is a slight local structure distortion due to Fe3＋ ions in ZnGa2O4：Fe3＋ crystals, but the site of Fe3＋ still retains D3d symmetry. On the other hand, it is found for Fe3＋ ions in ZnGa2O4：Fe3＋ crystals that the contribution to the SH parameters from the spin-orbit （SO） mechanism is the most important one, whereas the contributions to the SH parameters from other four mechanisms, including the spin-spin （SS）, spin-other-orbit （SOO）, orbit-orbit （OO）, and SO-SS-SOO-OO mechanisms, are small.

关 键 词：ZnGa2O4 FE3+ 局域结构畸变 自旋哈密顿参量 磁相互作用 

分 类 号：O731[理学—晶体学]