Friedrich, Florentine and Herrmann, Paul and Shanbhag, Shridhar Sanjay and Klimmer, Sebastian and Wilhelm, Jan and Soavi, Giancarlo (2026) Measurement of optically induced broken time-reversal symmetry in atomically thin crystals. NATURE PHOTONICS, 20. pp. 186-193. ISSN 1749-4885, 1749-4893
Full text not available from this repository. (Request a copy)Abstract
Time-reversal and space-inversion symmetries are fundamental properties of crystals and play a role in underlying phenomena such as magnetism, topology and non-trivial spin textures. Transition metal dichalcogenides (TMDs) represent an excellent tunable model system to explore the interplay between these symmetries as they can be engineered on demand by tuning the number of layers and via all-optical bandgap modulation. In this work, we modulate and study time-reversal symmetry in mono- and bilayer TMDs with all-optical methods using third-harmonic Faraday rotation. We excite the samples using elliptically polarized light, achieve spin-selective bandgap modulation and consequent breaking of time-reversal symmetry. The reduced symmetry modifies the nonlinear susceptibility tensor, causing a rotation of the emitted third-harmonic polarization. With this method, we probe broken time-reversal symmetry in both non-centrosymmetric (monolayer) and centrosymmetric (bilayer) WS2 crystals. Furthermore, we discuss how the detected third-harmonic rotation angle directly links to spin-valley locking in monolayer TMDs and spin-valley-layer locking in bilayer TMDs. Our results show a powerful approach to study broken time-reversal symmetry in crystals regardless of space-inversion symmetry, and shed light on the spin, valley and layer coupling of atomically thin semiconductors.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | VALLEY POLARIZATION; MONOLAYER; GENERATION; ROTATION |
| Subjects: | 500 Science > 530 Physics |
| Divisions: | Physics > Institute of Theroretical Physics Regensburg Center for UltrafastNanoscopy (RUN) |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 24 Jun 2026 06:26 |
| Last Modified: | 24 Jun 2026 06:26 |
| URI: | https://pred.uni-regensburg.de/id/eprint/66628 |
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