Ultrafast Triggering of Insulator-Metal Transition in Two-Dimensional VSe2

Deepnarayan Biswas, Alfred J.H. Jones, Paulina Majchrzak, Byoung Ki Choi, Tsung Han Lee, Klara Volckaert, Jiagui Feng, Igor Marković, Federico Andreatta, Chang Jong Kang, Hyuk Jin Kim, In Hak Lee, Chris Jozwiak, Eli Rotenberg, Aaron Bostwick, Charlotte E. Sanders, Yu Zhang, Gabriel Karras, Richard T. Chapman, Adam S. WyattEmma Springate, Jill A. Miwa, Philip Hofmann, Phil D.C. King, Young Jun Chang, Nicola Lanatà, Søren Ulstrup

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


The transition-metal dichalcogenide VSe2 exhibits an increased charge density wave transition temperature and an emerging insulating phase when thinned to a single layer. Here, we investigate the interplay of electronic and lattice degrees of freedom that underpin these phases in single-layer VSe2 using ultrafast pump-probe photoemission spectroscopy. In the insulating state, we observe a light-induced closure of the energy gap, which we disentangle from the ensuing hot carrier dynamics by fitting a model spectral function to the time-dependent photoemission intensity. This procedure leads to an estimated time scale of 480 fs for the closure of the gap, which suggests that the phase transition in single-layer VSe2 is driven by electron-lattice interactions rather than by Mott-like electronic effects. The ultrafast optical switching of these interactions in SL VSe2 demonstrates the potential for controlling phase transitions in 2D materials with light.

Original languageEnglish
Pages (from-to)1968-1975
Number of pages8
JournalNano Letters
Issue number5
StatePublished - 10 Mar 2021


  • Single-layer VSe
  • charge density wave
  • metal-insulator transition
  • time- and angle-resolved photoemission spectroscopy
  • ultrafast dynamics


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