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Enhanced Valley Polarization in WS2 /LaMnO3 Heterostructure
Jianchen Dang1,2, Mingwei Yang1,2, Xin Xie1,2
1Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
Researchers developed a WS2/LaMnO3 heterostructure achieving 80% valley polarization in monolayer tungsten disulfide (WS2) for valleytronics. This enhanced polarization persists to 160 K, overcoming intervalley scattering limitations.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Quantum Electronics
Background:
- Monolayer transition metal dichalcogenides (TMDs) show promise for valleytronics.
- Intervalley scattering typically limits valley polarization in TMDs.
Purpose of the Study:
- To enhance valley polarization in monolayer WS2.
- To investigate the mechanism behind enhanced valley polarization.
- To explore practical applications in valleytronics.
Main Methods:
- Fabrication of WS2/LaMnO3 thin film heterostructures.
- Nonresonant optical excitation at cryogenic temperatures (4.2 K).
- Temperature-dependent measurements of valley polarization and thermomagnetic curves.
Main Results:
- Achieved up to 80% valley polarization in monolayer WS2 using WS2/LaMnO3 heterostructures.
- Significantly higher polarization (80%) compared to WS2 on SiO2/Si (15%).
- Maintained high valley polarization (53%) up to 160 K.
- Demonstrated exciton-magnon coupling between WS2 and LaMnO3.
- Observed interlayer excitons with opposite valley polarizations.
Conclusions:
- WS2/LaMnO3 heterostructures enable significantly enhanced and temperature-stable valley polarization in monolayer WS2.
- Exciton-magnon coupling is the key mechanism for polarization enhancement.
- Ferromagnetic van der Waals engineering offers a viable route for practical valleytronic devices.
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