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arXiv · 2101.01523

Double Dirac Nodal Line Semimetal with Torus Surface State

Xiao-Ping Li·Botao Fu·Da-Shuai Ma·Chaoxi Cui·Zhi-Ming Yu·Yugui Yao
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Abstract

We propose a class of nodal line semimetals that host an eight-fold degenerate double Dirac nodal line (DDNL) with negligible spin-orbit coupling. We find only 5 of the 230 space groups host the DDNL. The DDNL can be considered as a combination of two Dirac nodal lines, and has a trivial Berry phase. This leads to two possible but completely different surface states, namely, a torus surface state covering the whole surface Brillouin zone and no surface state at all. Based on first-principles calculations, we predict that the hydrogen storage material LiBH is an ideal DDNL semimetal, where the line resides at Fermi level, is relatively flat in energy, and exhibits a large linear energy range. Interestingly, both the two novel surface states of DDNL can be realized in LiBH. Further, we predict that with a magnetic field parallel to DDNL, the Landau levels of DDNL are doubly degenerate due to Kramers-like degeneracy and have a doubly degenerate zero-mode.

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Xiao-Ping Li, Botao Fu, Da-Shuai Ma, Chaoxi Cui, Zhi-Ming Yu, Yugui Yao. 2021-01-05. Double Dirac Nodal Line Semimetal with Torus Surface State. https://doi.org/10.1103/physrevb.103.l161109

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