论文标题
软和各向异性本地时刻4 $ d $和5 $ d $混合价值M $ _2 $ o $ _9 $二聚体
Soft and anisotropic local moments in 4$d$ and 5$d$ mixed-valence M$_2$O$_9$ dimers
论文作者
论文摘要
我们通过对有限簇的确切对角度化进行了调查，该混合物含量六边形perovskites的电子结构和磁力含量为M $ _2 $ _9 $二聚体A $ _3 $ _3 $ _2 $ _2 $ $ $ $ _9 $，用于4 $ d $ d $ d $ d $ d $ d $ d $ d $ transition-transition-transition-transition-tryantition-metal metal mions mions o。我们发现，此类二聚体的磁矩是由自旋轨道耦合，Hund的耦合和库仑排斥的微妙相互作用以及M离子的电子填充来确定的。最重要的是，磁矩是各向异性和温度依赖性的。这种行为是自旋轨道耦合，磁场效应的结果，并且存在几乎几乎取代的电子构型，它们的接近度允许在室温下占用激发态。该分析与各种基于二聚体的材料的实验敏感性测量相一致。此外，我们对$ _3 $ b'm $ _2 $ o $ _9 $的材料进行了调查，并为实验相关的M填充物提出了地面相位图，$ d^{4.5} $，$ d^{3.5} $和$ d^{2.5} $。最后，我们的结果表明，通常在这些自旋轨道耦合材料中使用具有恒定磁矩的通常使用的curie-weiss定律。
We investigate via exact diagonalization of finite clusters the electronic structure and magnetism of M$_2$O$_9$ dimers in the mixed-valence hexagonal perovskites A$_3$B'M$_2$O$_9$ for various different fillings of 4$d$ and 5$d$ transition-metal M ions. We find that the magnetic moments of such dimers are determined by a subtle interplay of spin-orbit coupling, Hund's coupling, and Coulomb repulsion, as well as the electron filling of the M ions. Most importantly, the magnetic moments are anisotropic and temperature-dependent. This behavior is a result of spin-orbit coupling, magnetic field effects, and the existence of several nearly-degenerate electronic configurations whose proximity allows occupation of excited states already at room temperature. This analysis is consistent with experimental susceptibility measurements for a variety of dimer-based materials. Furthermore, we perform a survey of A$_3$B'M$_2$O$_9$ materials and propose ground-state phase diagrams for the experimentally relevant M fillings of $d^{4.5}$, $d^{3.5}$ and $d^{2.5}$. Finally, our results show that the usually applied Curie-Weiss law with a constant magnetic moment cannot be used in these spin-orbit-coupled materials.
