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arXiv 1604.05554cond-mat.mes-hall
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蜂窝状氧化物d $_{z^2}$流形中的Dirac拓扑绝缘体

Dirac topological insulator in the d$_{z^2}$ manifold of a honeycomb oxide

J. L. Lado, V. Pardo

摘要:

我们表明,通过从头计算和紧束缚模型,基于蜂窝晶格的氧化物系统可以维持拓扑非平凡的状态,如果一个单一的轨道占主导地位的光谱接近费米能级。在这种情况下,低能谱由两个Dirac方程描述,当自旋轨道耦合(SOC)被打开时,这两个Dirac方程变得非平凡地有间隙。我们讨论了实现这一点从传统的自旋半蜂窝反铁磁体,其状态接近费米能的d $_{z^2}$轨道。通过原子取代来关闭磁性,并确保电子结构变为二维,这足以使拓扑性在这样的系统中出现。我们发现,在这样的模型中的间隙与SOC线性缩放,而不是其他氧化物为基础的拓扑绝缘体,其中较小的间隙往往出现的晶格建设。我们还研究了这种体系中的量子霍尔效应,显示了与石墨烯物理的密切联系,但在d-电子系统中。

英文摘要:

We show by means of ab initio calculations and tight-binding modeling that an oxide system based on a honeycomb lattice can sustain topologically non-trivial states if a single orbital dominates the spectrum close to the Fermi level. In such situation, the low energy spectra is described by two Dirac equations that become non-trivially gapped when spin-orbit coupling (SOC) is switched on. We provide one specific example for this but the recipe is general. We discuss a realization of this starting from a conventional spin-a-half honeycomb antiferromagnet whose states close to the Fermi energy are d$_{z^2}$ orbitals. Switching off magnetism by atomic substitution and ensuring that the electronic structure becomes two-dimensional is sufficient for topologicality to arise in such a system. We show that the gap in such model scales linearly with SOC, opposed to other oxide-based topological insulators, where smaller gaps tend to appear by construction of the lattice. We also provide a study of the quantum Hall effect in such system, showing the close connections with the physics of graphene but in a d-electron system.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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