Observation of an anisotropic ultrafast spin relaxation process in large-area WTe2films

Yequan Chen, Zhendong Chen, Wenxuan Sun, Yongda Chen, Xianyang Lu, Xuezhong Ruan, Fengqiu Wang, Jing Wu, Liang He, Rong Zhang, Yongbing Xu*, Xuefeng Wang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Weyl semimetal Td-WTe2 hosts the natural broken inversion symmetry and strong spin-orbit coupling, which contains profound spin-related physics within a picosecond timescale. However, the comprehensive understanding of ultrafast spin behaviors in WTe2 is lacking due to its limited quality of large-scale films. Here, we report on an anisotropic ultrafast spin dynamics in highly oriented Td-WTe2 films using a femtosecond pump-probe technique at room temperature. A transient spin polarization-flip transition as fast as 0.8 ps is observed upon photoexcitation. The inversed spin is subsequently scattered by defects with a duration of about 5.9 ps. The whole relaxation process exhibits an intriguing dual anisotropy of sixfold and twofold symmetries, which stems from the energy band anisotropy of the WTe2 crystalline structure and the matrix element effect, respectively. Our work enriches the insights into the ultrafast opto-spintronics in topological Weyl semimetals.

Original languageEnglish
Article number163903
Number of pages7
JournalJournal of Applied Physics
Issue number16
Publication statusPublished - 27 Apr 2022

Bibliographical note

Funding Information:
We are grateful to F. Q. Song, C. F. Zhang, P. Wang, and B. Liu for fruitful discussions. This work was partially supported by the National Natural Science Foundation of China (NNSFC) (Grant Nos. 61822403, 11874203, and 11774160) and the National Key R&D Program of China (Grant Nos. 2017YFA0206304 and 2016YFA0300803).

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