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arXiv · 1605.04050

Topological nodal-line semimetals in alkaline-earth stannides, germanides and silicides

Huaqing Huang·Jianpeng Liu·David Vanderbilt·Wenhui Duan
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Abstract

Based on first-principles calculations and an effective Hamiltonian analysis, we systematically investigate the electronic and topological properties of alkaline-earth compounds $AX_2$ ($A$=Ca, Sr, Ba; $X$=Si, Ge, Sn). Taking BaSn$_2$ as an example, we find that when spin-orbit coupling is ignored, these materials are three-dimensional topological nodal-line semimetals characterized by a snake-like nodal loop in three-dimensional momentum space. Drumhead-like surface states emerge either inside or outside the loop circle on the (001) surface depending on surface termination, while complicated double-drumhead-like surface states appear on the (010) surface. When spin-orbit coupling is included, the nodal line is gapped and the system becomes a topological insulator with Z$_2$ topological invariants (1;001). Since spin-orbit coupling effects are weak in light elements, the nodal-line semimetal phase is expected to be achievable in some alkaline-earth germanides and silicides.

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Huaqing Huang, Jianpeng Liu, David Vanderbilt, Wenhui Duan. 2016-05-28. Topological nodal-line semimetals in alkaline-earth stannides, germanides and silicides. https://doi.org/10.1103/physrevb.93.201114

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