立方对称晶场中~6S(3d^5)态离子的磁相互作用及其自旋哈密顿参量的微观起源

Magnetic interactions as well as microscopic origins of the spin-Hamiltonian parameters for ~6S(3d^5) state ions in cubic symmetry crystal filed

基于完全对角化方法(complete diagonalization metho,CDM),研究了6S(3d5)态离子在立方对称晶场中的磁相互作用,分析了自旋哈密顿参量(a,g,Δg)的微观起源.研究中除了考虑研究者通常考虑的SO(spin-orbit)磁相互作用外,同时考虑了SS(spin-spin),SOO(spin-other-orbit),OO(orbit-orbit)磁相互作用.研究表明:6S(3d5)态离子在立方对称晶场中的自旋哈密顿参量起源于五种机理,即SO机理,SS机理,SOO机理,OO机理以及SO-SS-SOO-OO联合作用机理.文中研究了五种机理的相对重要性,结果表明:SO机理与SO-SS-SOO-OO联合作用机理在五种机理中最为重要.尽管SS,SOO,OO磁相互作用单独作用时对自旋哈密顿参量的贡献很小,但它们的联合作用SO-SS-SOO-OO机理对自旋哈密顿参量的贡献非常可观.此外研究表明:零场分裂参量a主要来自纯自旋四重态及自旋二重态与自旋四重态联合作用的贡献,而Zeeman g(或者Δg)因子主要来自纯自旋四重态的贡献.纯自旋二重态对自旋哈密顿参量a与g(或者Δg)的贡献为零.在我们所选择的晶场区域,发现下列关系始终成立:a>0,a(-|Dq|)<a(|Dq|),g(-Dq)=g(Dq),a(-Dq,-ξd,B,C)=a(Dq,ξd,B,C),Δg(-Dq,-ξd,B,C)=Δg(Dq,ξd,B,C).作为本文理论的应用,研究了四种典型的Mn2+掺杂晶体材料,即Mn2+:KZnF3,Mn2+:RbCdF3,Mn2+:MgO,Mn2+:CaO,理论与实验测量符合很好.

The magnetic interactions as well as the microscopic origins of the spin-Hamiltonian（SH） parameters including a, g, and Ag for 6S（3d5） state ion in cubic symmetry crystal field, taking into account the spin-spin （SS）, the spin-other-orbit （SOO）, the orbit-orbit （OO） magnetic interactions besides the well-known spin-orbit （SO） magnetic interaction, have been investigated using the complete diagonalization method （CDM）. It is shown that the SH parameters arise from the five microscopic mechanisms of SO coupling, SS coupling, SOO coupling, OO coupling, and SO-SS-SOO-OO combined coupling. The relative importance of the contributions of the mechanisms to the SH parameters are investigated. It is shown that the SO coupling mechanism and the SO-SS-SOO-OO combined coupling mechanism are the most important of these coupling mechanisms. The contributions from SS coupling mechanism, SOO coupling mechanism, OO coupling mechanism to the SH parameter are quite small but their combined effects （SO-SS-SOO-OO combined coupling mechanism） is appreciable. The zero-field splitting （ZFS） arises from the net spin quartet states as well as the combined effects between the spin doublet states and the spin quartets states whereas the Zeeman g （or Ag）factor arises from the net spin quartet states. The contributions to the SH parameters from the net spin doublet states are zero. It is found that the relations ： a 〉 0, a （ - ｜ Dq ｜ ） 〈 a （｜ Dq ｜ ）, g （ - Dq ） = g （ Dq ）, a （ - Dq, ξd, B, C）= a（Dq,ξd, B, C） andAg（- Dq, - ξa, B, C） =Ag（Dq, ξd, B, C） always hold for the selected crystal field area. Illustrative evaluations are performed for the four typical materials. Mn2^＋ ： KZnF3 , Mn2^＋ ： RbCdF3 , Mn2^＋： MgO and Mn2^＋ ： CaO. Good agreement between the theoretical values and the experimental results are obtained.