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arXiv · 1504.03492

Topological semimetals and topological insulators in rare earth monopnictides

Minggang Zeng·Chen Fang·Guoqing Chang·Yu-An Chen·Timothy Hsieh·Arun Bansil·Hsin Lin·Liang Fu
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Abstract

We use first principles calculations to study the electronic properties of rock salt rare earth monopnictides La$X$ ($X=$N, P, As, Sb, Bi). A new type of topological band crossing termed `linked nodal rings' is found in LaN when the small spin-orbital coupling (SOC) on nitrogen orbitals is neglected. Turning on SOC gaps the nodal rings at all but two points, which remain gapless due to $C_4$-symmetry and leads to a 3D Dirac semimetal. Interestingly, unlike LaN, compounds with other elements in the pnictogen group are found to be topological insulators (TIs), as a result of band reordering due to the increased lattice constant as well as the enhanced SOC on the pnictogen atom. These TI compounds exhibit multi-valley surface Dirac cones at three $\bar{M}$-points on the $(111)$-surface.

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Minggang Zeng, Chen Fang, Guoqing Chang, Yu-An Chen, Timothy Hsieh, Arun Bansil, Hsin Lin, Liang Fu. 2015-04-14. Topological semimetals and topological insulators in rare earth monopnictides. https://arxiv.org/abs/1504.03492

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