Journal
PHYSICAL REVIEW LETTERS
Volume 129, Issue 2, Pages -Publisher
AMER PHYSICAL SOC
DOI: 10.1103/PhysRevLett.129.027401
Keywords
-
Categories
Funding
- Basic Science Center Project of NSFC [51788104]
- Beijing Advanced Innovation Center for Future Chip
- Cambridge Trust
- Winton Programme for the Physics of Sustainability
- UKRI Future Leaers Fellowship [MR/V023926/1]
- Gianna Angelopoulos Programme for Science, Technology, and Innovation
Ask authors/readers for more resources
This study explores the fundamental limits of valley polarization through phonon-mediated optical absorption and reveals that the valley polarization is around 70% at room temperature for state-of-the-art valleytronic materials. This finding suggests that sufficiently pure transition-metal dichalcogenides are ideal candidates for valleytronics applications.
The ability to selectively photoexcite at different Brillouin zone valleys forms the basis of valleytronics and other valley-related physics. Symmetry arguments combined with static lattice first-principles calculations suggest an ideal 100% valley polarization in transition-metal dichalcogenides under circularly polarized light. However, experimental reports of the valley polarization range from 32% to almost 100%. Possible explanations for this discrepancy include phonon-mediated transitions, which would place a fundamental limit to valley polarization, and defect-mediated transitions, which could, in principle, be reduced with cleaner samples. We explore the phonon-mediated fundamental limit by performing calculations of phonon-mediated optical absorption for circularly polarized light entirely from the first principles. We also use group theory to reveal the microscopic mechanisms behind the phonon-mediated excitations, discovering contributions from several individual phonon modes and from multiphonon processes. Overall, our calculations show that the phonon-limited valley polarization is around 70% at room temperature for state-of-the-art valleytronic materials including MoSe2, MoS2, WS2, WSe2, and MoTe2. This fundamental limit implies that sufficiently pure transition-metal dichalcogenides are ideal candidates for valleytronics applications.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available