Assembling transition metal dichalcogenides (TMDCs) at the two-dimensional (2D) limit is a promising approach for tailoring emerging states of matter such as superconductivity or charge density waves (CDWs). Single-layer (SL) VSe2 stands out in this regard because it exhibits a strongly enhanced CDW transition with a higher transition temperature compared to the bulk in addition to an insulating phase with an anisotropic gap at the Fermi level, causing a suppression of anticipated 2D ferromagnetism in the material. Here, we investigate the interplay of electronic and lattice degrees of freedom that underpin these electronic phases in SL VSe2 using ultrafast pump-probe photoemission spectroscopy. In the insulating state, we observe a light-induced closure of the energy gap on a timescale of 480 fs, which we disentangle from the ensuing hot carrier dynamics. Our work thereby reveals that the phase transition in SL VSe2 is driven by electron-lattice coupling and demonstrates the potential for controlling electronic phases in 2D materials with light.
@article{arxiv.2007.13355,
title = {Ultrafast triggering of insulator-metal transition in two-dimensional VSe$_2$},
author = {Deepnarayan Biswas and Alfred J. H. Jones and Paulina Majchrzak and Byoung Ki Choi and Tsung-Han Lee and Klara Volckaert and Jiagui Feng and Igor Marković and Federico Andreatta and Chang-Jong Kang and Hyuk Jin Kim and In Hak Lee and Chris Jozwiak and Eli Rotenberg and Aaron Bostwick and Charlotte E. Sanders and Yu Zhang and Gabriel Karras and Richard T. Chapman and Adam S. Wyatt and Emma Springate and Jill A. Miwa and Philip Hofmann and Phil D. C. King and Young Jun Chang and Nicola Lanata and Søren Ulstrup},
journal= {arXiv preprint arXiv:2007.13355},
year = {2021}
}
Comments
23 pages including supplementary information, 3 figures in the main text and 6 figures in the supplemental text