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arXiv · 1910.06178

Photoninduced Weyl half-metal phase and spin filter effect from topological Dirac semimetals

Xiao-Shi Li·Chen Wang·Ming-Xun Deng·Hou-Jian Duan·Pei-Hao Fu·Rui-Qiang Wang·L. Sheng·D. Y. Xing
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Abstract

Recently discovered Dirac semimetals (DSMs) with two Dirac nodes, such as Na$_{3}$Bi and Cd$_{2}$As$_{3}$, are regarded to carry the $\mathbb{Z}_{2}$ topological charge in addition to the chiral charge. Here, we study the Floquet phase transition of $\mathbb{Z}_{2}$ topological DSMs subjected to a beam of circularly polarized light. Due to the resulting interplay of the chiral and $\mathbb{Z}_{2}$ charges, the Weyl nodes are not only chirality-dependent but also spin-dependent, which constrains the behaviors in creation and annihilation of the Weyl nodes in pair. Interestingly, we find a novel phase: One spinband is in Weyl semimetal phase while the other spinband is in insulator phase, and we dub it Weyl half-metal (WHM) phase. We further study the spin-dependent transport in a Dirac-Weyl semimetal junction and find a spin filter effect as a fingerprint of existence of the WHM phase. The proposed spin filter effect, based on the WHM bulk band, is highly tunable in a broad parameter regime and robust against magnetic disorder, which is expected to overcome the shortcomings of the previously proposed spin filter based on the topological edge/surface states. Our results offer a unique opportunity to explore the potential applications of topological DSMs in spintronics.

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Xiao-Shi Li, Chen Wang, Ming-Xun Deng, Hou-Jian Duan, Pei-Hao Fu, Rui-Qiang Wang, L. Sheng, D. Y. Xing. 2019-10-14. Photoninduced Weyl half-metal phase and spin filter effect from topological Dirac semimetals. https://doi.org/10.1103/physrevlett.123.206601

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