BaCrSi_4O_(10)与AgGaSe_2:Cr^(2+)吸收光谱的精细结构及自旋单态对零场分裂参量的影响  

Effects of fine structure of absorption spectrum and spin-singlet on zero-field-splitting parameters for BaCrSi_4O_(10) and AgGaSe_2:Cr^(2+)

作　　者：谭晓明[1] 赵刚[1] 张迪[2] 

机构地区：[1]鲁东大学物理与光电工程学院,烟台264025 [2]鲁东大学交通学院,烟台264025

出　　处：《物理学报》2016年第10期294-299,共6页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11204121);山东省自然科学基金(批准号:ZR2011AL021)资助的课题~~

摘　　要：在强场图像中构造了四角对称环境中Cr^(2+)离子包括自旋单态在内的完全能量矩阵,通过对角化能量矩阵方法,计算得到了BaCrSi_4O_(10)与AgGaSe_2:Cr^(2+)吸收光谱的精细结构及自旋单态对零场分裂参量的影响.从理论上给出了BaCrSi_4O_(10)与AgGaSe_2:Cr^(2+)吸收光谱的精细结构及BaCrSi4_O_(10)的零场分裂参量值.计算结果显示自旋单态对零场分裂参量D的影响完全可忽略,但对a和F的影响比较大.这种影响主要来自自旋-轨道耦合导致的自旋五重态与自旋三重态和自旋单态的相互作用,而自旋轨道耦合的选择定则显示自旋单态并非直接影响五重态而是通过自旋三重态间接地影响基态的五重态.因此,为了得到准确的零场分裂参量值,所有的自旋态都应该考虑.The compounds doped with or containing Cr^2＋ ions are extensively used as optoelectronic and nonlinear optical materials,because they have special optical,magnetic and electric properties.These properties are very closely related to the absorption spectra and zero-field-splitting.The studies of the absorption spectra and zero-field-splitting are very important for realizing the doped microscopic mechanism and understanding the interaction between impurity ions and host crystals,and they may be useful to material designers.The concept of the standard basis adapted to the double group chain is adopted in the strong-field scheme by the crystal field theory.This concept emphasizes the standardization of the basis of the whole 3d^4 configuration space including all spin states.Thus,the basis functions can be constructed according to each irreducible representation of the double group and each basis function has a certain expression.Each standard basis adapted to the double group chain can be built from the former by a linear transformation,which forms a basis chain.Thus,the complete energy matrix including spin singlet is constructed for Cr^2＋ ion in tetragonal symmetry environment in the strong-field-representation by the crystal field theory.The fine structures of absorption spectra and the spin-singlet contributions to zero-field-splitting parameters for BaCrSi4O-10 and Ag GaSe2：Cr＋are studied by diagonalizing the complete energy matrix.The fine structures for the two systems and the zero-field-splitting parameters for BaCrSi4O-10 are given theoretically for the first time.The fine structures are assigned by the irreducible representation of the group.The results show that the spin-singlet contribution to D is negligible,but the contributions to a and F are important.The contributions arise from the interaction of the spin quintuplets with both spin triplets and spin singlets via spin-orbit coupling.However,the selection rule of spin-orbit coupling shows that the spin singlets do not affect the quintuplets

关 键 词：吸收光谱 精细结构 自旋单态 

分 类 号：O433.51[机械工程—光学工程]