Raiber, Simon and Faria Junior, Paulo E. and Falter, Dennis and Feldl, Simon and Marzena, Petter and Watanabe, Kenji and Taniguchi, Takashi and Fabian, Jaroslav and Schueller, Christian (2022) Ultrafast pseudospin quantum beats in multilayer WSe2 and MoSe2. NATURE COMMUNICATIONS, 13 (1): 4997. ISSN , 2041-1723
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Here, the authors investigate excitonic transitions in mono- and multi-layer WSe2 and MoSe2 by time-resolved Faraday ellipticity (TRFE) with in-plane magnetic fields, and attribute the oscillatory TRFE signal in the multilayer samples to pseudospin quantum beats of excitons, a manifestation of spin- and pseudospin layer locking. Layered van-der-Waals materials with hexagonal symmetry offer an extra degree of freedom to their electrons, the so-called valley index or valley pseudospin, which behaves conceptually like the electron spin. Here, we present investigations of excitonic transitions in mono- and multilayer WSe2 and MoSe2 materials by time-resolved Faraday ellipticity (TRFE) with in-plane magnetic fields, B-parallel to, of up to 9 T. In monolayer samples, the measured TRFE time traces are almost independent of B-parallel to, which confirms a close to zero in-plane exciton g factor g(parallel to), consistent with first-principles calculations. In contrast, we observe pronounced temporal oscillations in multilayer samples for B-parallel to > 0. Our first-principles calculations confirm the presence of a non-zero g(parallel to) for the multilayer samples. We propose that the oscillatory TRFE signal in the multilayer samples is caused by pseudospin quantum beats of excitons, which is a manifestation of spin- and pseudospin layer locking in the multilayer samples.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | SPIN COHERENCE; MONOLAYER; EXCITONS; EXCITATIONS; DIFFUSION; ELECTRONS; LAYER; |
| Subjects: | 500 Science > 530 Physics |
| Divisions: | Physics > Institute of Theroretical Physics > Chair Professor Richter > Group Jaroslav Fabian Physics > Institute of Experimental and Applied Physics > Chair Professor Lupton > Group Christian Schüller |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 09 Jan 2024 09:44 |
| Last Modified: | 09 Jan 2024 09:44 |
| URI: | https://pred.uni-regensburg.de/id/eprint/57110 |
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