Npj Comput. Mater.: 氧化物中的拓扑态—如何不再众里寻她千百度？
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复杂氧化物表现出非常丰富的物理现象，包括莫特绝缘体，多铁性和高温超导。并且寻找非平庸拓扑态已经成为凝聚态物理领域最热门的课题之一。在钙钛矿氧化物中，因过渡金属原子在(111)方向特有的蜂巢结构，这些体系被预言可实现量子自旋霍尔态。但由于在实验上制备(111)方向生长的钙钛矿氧化物非常困难，因此一直没有显著的进展。该研究选用多种不同过渡金属钙钛矿氧化物，提出了一种在（001）方向堆叠构建(SrMO3)1/(SrM’O3)1氧化物超晶格的方法。
该文近期发表于npj Computational Materials 8：208(2022)，英文标题与摘要如下，点击左下角“阅读原文”可以自由获取论文PDF。
Emergent topological states via digital (001) oxide superlattices
Zhiwei Liu, Hongquan Liu, Jiaji Ma, Xiaoxuan Wang, Gang Li & Hanghui Chen
Oxide heterostructures exhibit many intriguing properties. Here we provide design principles for inducing multiple topological states in (001) (AMO3)1/(AM’O3)1 oxide superlattices. Aided by first-principles calculations and model analysis, we show that a (SrMO3)1/(SrM’O3)1 superlattice (M = Nb, Ta and M’ = Rh, Ir) is a strong topological insulator with Z2 index (1;001). More remarkably, a (SrMoO3)1/(SrIrO3)1 superlattice exhibits multiple coexisting topological insulator (TI) and topological Dirac semi-metal (TDS) states. The TDS state has a pair of type-II Dirac points near the Fermi level and symmetry-protected Dirac node lines. The surface TDS Dirac cone is sandwiched by two surface TI Dirac cones in the energy-momentum space. The non-trivial topological properties arise from the band inversion between d orbitals of two dissimilar transition metal atoms and a particular parity property of (001) superlattice geometry. Our work demonstrates how to induce non-trivial topological states in (001) perovskite oxide heterostructures by rational design.
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