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Ultrafast Triggering of Insulator-Metal Transition in Two-Dimensional VSe2
Deepnarayan Biswas1, Alfred J H Jones1, Paulina Majchrzak1,2
1Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark.
Nano Letters
|February 18, 2021
Summary
Single-layer vanadium diselenide (VSe2) shows an insulating phase driven by electron-lattice interactions. Ultrafast spectroscopy reveals light can control this phase transition in 2D materials.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Surface Science
Background:
- Single-layer VSe2 exhibits unique electronic properties, including an enhanced charge density wave transition temperature and an emergent insulating phase.
- Understanding the fundamental mechanisms driving these phases is crucial for novel electronic applications.
Purpose of the Study:
- To investigate the interplay between electronic and lattice degrees of freedom in single-layer VSe2.
- To elucidate the mechanism behind the insulating phase and its response to external stimuli.
Main Methods:
- Ultrafast pump-probe photoemission spectroscopy was employed to study the dynamics of single-layer VSe2.
- A model spectral function was fitted to time-dependent photoemission intensity data to disentangle energy gap closure from carrier dynamics.
Main Results:
- A light-induced closure of the energy gap was observed in the insulating state of single-layer VSe2.
- The estimated timescale for gap closure was 480 fs, indicating a rapid electronic response.
- The results suggest that electron-lattice interactions, not Mott-like effects, drive the phase transition.
Conclusions:
- The phase transition in single-layer VSe2 is primarily driven by electron-lattice interactions.
- Ultrafast optical control of these interactions demonstrates the potential for light-driven phase switching in 2D materials.
- This work opens avenues for developing novel optoelectronic devices based on 2D transition-metal dichalcogenides.
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