Inversion asymmetric topological insulator promises great potential to realize many intriguing phenomena such as intrinsic topological [Formula: see text]–[Formula: see text] junctions, pyroelectricity and novel topological magneto-electric effects that require inversion asymmetry. Recently, gapless helical surface Dirac fermions were observed in inversion-asymmetric BiTeCl crystal. However, heavy debate about whether BiTeCl is a topological insulator and controversial experimental results of the electronic structure of BiTeCl exist. In this work, through ab-initio calculations, we discovered that a BiTeCl-dominant BiTeCl/Bi2Te3 heterostructure can give rise to the observed band structures with a single surface Dirac fermion. Interestingly, we further suggest that such a BiTeCl/Bi2Te3 heterostructure could be naturally formed by annealing pure BiTeCl single crystals. Our results not only resolve the discrepancy between the previous experiments on heat treated samples and theoretical investigations, but also point out a pathway to design novel materials with sophisticated properties.

中文翻译：

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基于 BiTeCl 的异质结构中的拓扑表面狄拉克费米子

反转不对称拓扑绝缘体有望实现许多有趣的现象，例如本征拓扑[公式：见正文]-[公式：见正文]结、热电和需要反转不对称的新型拓扑磁电效应。最近，在反型不对称 BiTeCl 晶体中观察到无间隙螺旋表面狄拉克费米子。然而，关于 BiTeCl 是否是拓扑绝缘体的激烈争论和 BiTeCl 电子结构的有争议的实验结果仍然存在。在这项工作中，通过从头算计算，我们发现以 BiTeCl 为主的 BiTeCl/Bi2碲3异质结构可以产生具有单个表面狄拉克费米子的观察到的能带结构。有趣的是，我们进一步建议这样的 BiTeCl/Bi2碲3通过对纯 BiTeCl 单晶进行退火可以自然形成异质结构。我们的结果不仅解决了先前热处理样品实验与理论研究之间的差异，而且指出了设计具有复杂性能的新型材料的途径。