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.
@article{arxiv.2008.08785,
title = {Anisotropic ultrafast spin/valley dynamics in WTe2 films},
author = {Yequan Chen and Zhendong Chen and Yongda Chen and Liming Chen and Jiai Ning and Bo Liu and Chunchen Zhang and Xianyang Lu and Xuezhong Ruan and Wenqing Liu and Peng Wang and Fengqi Song and Chunfeng Zhang and Fengqiu Wang and Jing Wu and Liang He and Xuefeng Wang and Rong Zhang and Yongbing Xu},
journal= {arXiv preprint arXiv:2008.08785},
year = {2023}
}