SnTiO_3:Mn^(4+)晶体中荷移激发态对EPRg和零场分裂D贡献的研究

Studies on contribution of the charge transfer excited states to EPRg factors and the zero-field splitting D in SnTiO_3: Mn^(4+) crystals.

构建了四方八面体(MnO6)8-络离子g因子和零场分裂D的完全高阶微扰公式.在这些公式中,除了中心离子Mn4+和配体离子O2-自旋-轨道耦合对g因子和D的贡献(双SO耦合参数模型)外,也考虑了荷移激发态(与电荷转移谱有关)与基态混合对EPR参量的贡献.用此公式算得SnTiO3:Mn4+的g因子和D与实验值较一致.而单SO耦合参数模型和双SO耦合参数模型获得的g因子和D较大地偏离了实验值.这说明SnTiO3:Mn4+晶体g因子的计算中荷移激发态与基态的相互作用不能被忽略.

The complete high order perturbation formulas are established for g factors and the zero-field splitting D in the tetragonal octahedral（MnO6）8-clusters.In the formulas,both the contribution of the spin-orbit coupling of the central ion Mn4＋ and ligand ion O2-,and the contribution of overlaps of the charge transfer excited states and ground states are considered.The calculated g and D are in agreement with the observed ones for SnTiO3： Mn4＋.But the calculated g and D from the one-SO-parameter model and the two-SO-parameter model deviate much greater from the observed one.It is showed that the function of the charge transfer excited states and ground states can not be omitted in SnTiO3： Mn4＋.