Strong influence of nonmagnetic ligands on the momentum-dependent spin splitting in antiferromagnets
Strong influence of nonmagnetic ligands on the momentum-dependent spin splitting in antiferromagnets
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DOI：
10.1103/physrevb.103.224410
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发表时间：
2021-03
期刊：
影响因子：
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通讯作者：
Linding Yuan;Zhi Wang;Jun-Wei Luo;A. Zunger
中科院分区：
文献类型：
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作者：
Linding Yuan;Zhi Wang;Jun-Wei Luo;A. Zunger
最近的研究表明，非相对论反铁磁有序可以产生类似于拉什巴效应的动量依赖性自旋分裂，但不需要相对论自旋轨道耦合。虽然这些化合物的分类可以通过对称分析和密度泛函理论计算中的不同自旋分裂原型（SST）来说明，但这些不同化合物的化学键和结构的巨大变化可能掩盖了这样的问题：自旋分裂的变化有多少可以追溯到对称定义的特征，而不是底层的化学和结构多样性。替代模型哈密顿方法不面临化学和结构复杂性问题，但通常仅考虑磁性亚晶格，通过重新规范化磁性位点之间的相互作用来处理非磁性配体的所有重要影响。为此，我们构建了一个 DFT 模型哈密顿量，使我们能够在恒定化学条件下研究海表面温度，同时保留包括配体在内的真实原子尺度结构。这是通过使用单一通用磁性骨架晶格（岩盐 NiO 中的 Ni2+ 离子）并设计非磁性（氧）亚晶格的小位移来实现的，该亚晶格通过设计产生不同的 SST 磁对称性。我们表明，（i）即使具有非常相似的能带结构的相似晶体结构也可能导致自旋分裂与动量的对比行为，以及（ii）即使非磁性配体亚晶格的细微变形也可能导致 AFM 诱导的 SST 中巨大的自旋分裂。这是相对于不考虑介导间接磁相互作用（例如超交换）的非磁性配体的磁体建模惯例的范式转变。
Recent studies show the nonrelativistic antiferromagnetic ordering could generate momentum-dependent spin splitting analogous to the Rashba effect but free from the requirement of relativistic spin-orbit coupling. Whereas the classification of such compounds can be illustrated by different spin-splitting prototypes (SSTs) from symmetry analysis and density-functional-theory calculations, the huge variation in chemical bonding and structures of these diverse compounds possibly clouds the issue of how much of the variation in spin splitting can be traced back to the symmetry-defined characteristics, rather to the underlining chemical and structural diversity. The alternative model Hamiltonian approaches do not confront the issues of chemical and structural complexity but often consider only the magnetic sublattice, dealing with the all-important effects of the nonmagnetic ligands via renormalizing the interactions between the magnetic sites. To this end, we constructed a DFT model Hamiltonian that allows us to study SSTs at constant chemistry while retaining the realistic atomic-scale structure including ligands. This is accomplished by using a single, universal magnetic skeletal lattice (Ni2+ ions in rocksalt NiO) and designing small displacements of the nonmagnetic (oxygen) sublattice which produce, by design, the different SST magnetic symmetries. We show that (i) even similar crystal structures having very similar band structures can lead to contrasting behavior of spin splitting vs momentum, and (ii) even subtle deformations of the nonmagnetic ligand sublattice could cause a giant spin splitting in AFM-induced SST. This is a paradigm shift relative to the convention of modeling magnets without considering the nonmagnetic ligand that mediates indirect magnetic interaction (e.g., superexchange).