Room-Temperature Valley Polarization in Atomically Thin Semiconductors via Chalcogenide Alloying
Sheng Liu1, Andrés Granados Del Águila1, Xue Liu1
1Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore.
ACS Nano
|August 19, 2020
Summary
Researchers achieved room-temperature control of valley polarization in transition-metal dichalcogenides (TMDs) using chalcogenide alloying. This breakthrough enables efficient manipulation of electronic properties for future opto-valleytronics devices.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Quantum Information Science
Background:
- Valley pseudospin and spin degrees of freedom are key for quantum information processing.
- Opto-valleytronics devices utilize light polarization to control electronic properties in transition-metal dichalcogenides (TMDs).
- Achieving room-temperature valley polarization in TMDs optically has been a significant challenge.
Purpose of the Study:
- To demonstrate robust room-temperature control of valley polarization and quantum coherence in atomically thin TMDs.
- To investigate the role of Coulomb forces and spin-orbit interactions in valley pseudospin dynamics.
- To establish a comprehensive approach for efficient manipulation of valley pseudospin for opto-valleytronics.
Main Methods:
- Chalcogenide alloying in atomically thin TMDs to engineer Coulomb forces and spin-orbit interactions.
- Strategic design of carrier density and the order of optically active/forbidden states.
- Optical excitation with polarized light to generate and probe valley polarization.
Main Results:
- Demonstrated strong valley polarization (up to ~50%) and valley quantum coherence (up to ~20%) at room temperature.
- Showcased the ability to control valley pseudospin dynamics by tuning the chalcogenide atom ratio.
- Established a method for intrinsic and efficient manipulation of valley pseudospin and spin degrees of freedom.
Conclusions:
- Chalcogenide alloying provides a powerful route for room-temperature opto-valleytronic applications.
- Tailoring material properties through alloying enables precise control over valley pseudospin dynamics.
- This work lays the foundation for developing practical opto-valleytronics devices.
Keywords:
alloyed TMD monolayerselectron−hole exchange interactionexciton fine structureroom-temperature valley polarizationspin−orbit engineeringvalley pseudospin dynamicsMore Related Videos
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