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Dirac and Weyl Semimetals in Sn1−xInxTe
Physica Status Solidi-Rapid Research Letters ( IF 2.5 ) Pub Date : 2020-09-03 , DOI: 10.1002/pssr.202000362
Tome M. Schmidt 1 , Gyaneshwa P. Srivastava 2
Affiliation  

SnTe is a well‐characterized topological crystalline insulator material with an inverted bandgap at the L point in the fcc Brillouin zone, whereas Sn1–xInxTe is a superconductor. By utilizing first‐principles and topological invariant calculations, we find distinct topological phase transitions in Sn1–xInxTe as a function of In content and crystal symmetry. For low In content, the inverted bandgap is maintained and the nontrivial insulator phase is unaffected. For In content x ≥ 0.12, one of the bands is reverted, maintaining an odd number of inverted bands. The reverted band connects valence and conduction bands, forming a Dirac‐like crossing close to the Fermi level, protected by crystal symmetry. Breaking of the inversion symmetry splits the fourfold degenerate Dirac crossing into pairs of Weyl nodes with opposite chirality. It is shown that this symmetry breaking can be performed by a ferroelectric effect, or by a Jahn–Teller distortion leading to a Weyl scenario. A phase diagram is predicted as a function of In content and the crystal symmetry, with topological crystalline insulator, Dirac and Weyl semimetal phases. The findings show that topological insulators can be used to realize a rich variety of fermions, especially when doping can induce reversion of inverted bands.

中文翻译:

Sn1-xInxTe中的Dirac和Weyl半金属

SnTe是一种表征良好的拓扑晶体绝缘体材料,在fcc布里渊区的L点具有带隙反向,而Sn 1- x In x Te是超导体。通过利用第一性原理和拓扑不变性计算,我们发现Sn 1– x In x Te中不同的拓扑相变是In含量和晶体对称性的函数。对于低的In含量,可保持反向带隙且不平凡的绝缘体相不受影响。对于内容x ≥0.12,其中一个频段会被还原,并保持奇数个反相频段。反向带连接价带和导带,形成接近费米能级的狄拉克型交叉,并受到晶体对称性的保护。反转对称性的破坏将四倍简并Dirac交叉分裂为具有相反手性的Weyl节点对。结果表明,这种对称破坏可以通过铁电效应来实现,也可以通过导致Weyl场景的Jahn-Teller畸变来实现。预测了一个相图,该图是In含量和晶体对称性的函数,具有拓扑晶体绝缘体,Dirac和Weyl半金属相。研究结果表明,拓扑绝缘体可用于实现各种各样的费米子,尤其是当掺杂会导致倒带反转时。
更新日期:2020-11-02
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