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arXiv · 2008.08785

Anisotropic ultrafast spin/valley dynamics in WTe2 films

Yequan Chen·Zhendong Chen·Yongda Chen·Liming Chen·Jiai Ning·Bo Liu·Chunchen Zhang·Xianyang Lu·Xuezhong Ruan·Wenqing Liu·Peng Wang·Fengqi Song·Chunfeng Zhang·Fengqiu Wang·Jing Wu·Liang He·Xuefeng Wang·Rong Zhang·Yongbing Xu
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Abstract

WTe2 Weyl semimetal hosts the natural broken inversion symmetry and strong spin orbit coupling, making it promising for exotic spin/valley dynamics within a picosecond timescale. Here, we unveil an anisotropic ultrafast spin/valley dynamics in centimeter-scale, single-crystalline Td-WTe2 films using a femtosecond pump-probe technique at room temperature. We observe a transient (~0.8 ps) intra-valley transition and a subsequent polarization duration (~5 ps) during the whole spin/valley relaxation process. Furthermore, the relaxation exhibits the remarkable anisotropy of approximately six-fold and two-fold symmetries due to the intrinsic anisotropy along the crystalline orientation and the extrinsic matrix element effect, respectively. Our results offer a prospect for the ultrafast manipulation of spin/valleytronics in topological quantum materials for dissipationless high-speed spin/valleytronic devices.

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Yequan Chen, Zhendong Chen, Yongda Chen, Liming Chen, Jiai Ning, Bo Liu, Chunchen Zhang, Xianyang Lu, Xuezhong Ruan, Wenqing Liu, Peng Wang, Fengqi Song, Chunfeng Zhang, Fengqiu Wang, Jing Wu, Liang He, Xuefeng Wang, Rong Zhang, Yongbing Xu. 2020-08-20. Anisotropic ultrafast spin/valley dynamics in WTe2 films. https://doi.org/10.1063/5.0090935

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