Surface state evolution induced by magnetic order in axion insulator candidate EuIn2As2
Surface state evolution induced by magnetic order in axion insulator candidate EuIn2As2
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DOI：
10.1103/physrevb.106.125156
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发表时间：
2022-09
期刊：
影响因子：
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通讯作者：
Mingda Gong;Divyanshi Sar;J. Friedman;D. Kaczorowski;S. Razek;Wei‐Cheng Lee;P. Aynajian
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文献类型：
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作者：
Mingda Gong;Divyanshi Sar;J. Friedman;D. Kaczorowski;S. Razek;Wei‐Cheng Lee;P. Aynajian
，狄拉克表面态通过时间反演对称性破缺的间隙可以实现凝聚态物质中的轴子绝缘体态。尽管付出了巨大的努力，但只有少数材料系统属于本征磁拓扑绝缘体 (TI) 类别。最近的理论计算提出反铁磁EuIn 2 As 2 是一种具有带隙表面态的拓扑非平凡磁绝缘体。在这里，我们使用扫描隧道显微镜和光谱学 (STM/STS) 辅以密度泛函理论 (DFT) 计算和建模来探测 EuIn 2 As 2 中的表面电子态。我们发现自旋轨道引起的体能隙约为 120 meV，仅比费米能高几 meV，其中存在拓扑表面态。与温度相关的测量提供了在低于 AFM 级的低温下表面态的部分带隙 (~ 40 meV) 的证据，该部分带隙随着温度的升高而减小，但在高于 T N 时仍然有限。
, Gapping of Dirac surface states through time reversal symmetry breaking may realize the axion insulator state in condensed matter. Despite tremendous efforts, only a few material systems fall in this category of intrinsic magnetic topological insulators (TI). Recent theoretical calculations proposed the antiferromagnetic EuIn 2 As 2 to be a topologically non-trivial magnetic insulator with gapped surface states. Here we use scanning tunneling microscopy and spectroscopy (STM/STS) complemented with density-functional theory (DFT) calculations and modelling to probe the surface electronic states in EuIn 2 As 2 . We find a spin-orbit induced bulk gap of ~ 120 meV located only a few meV above the Fermi energy, within which topological surface states reside. Temperature dependent measurements provide evidence of the partial gapping ( ~ 40 meV) of the surface states at low temperatures below the AFM order, which decreases with increasing temperature but remains finite above T N .