Using femtosecond time-resolved photoelectron spectroscopy we demonstrate that photoexcitation transforms monoclinic VO2 quasi-instantaneously into a metal. Thereby, we exclude an 80 fs structural bottleneck for the photoinduced electronic phase transition of VO2. First-principles many-body perturbation theory calculations reveal a high sensitivity of the VO2 band gap to variations of the dynamically screened Coulomb interaction, supporting a fully electronically driven isostructural insulator-to-metal transition. We thus conclude that the ultrafast band structure renormalization is caused by photoexcitation of carriers from localized V 3d valence states, strongly changing the screening before significant hot-carrier relaxation or ionic motion has occurred.

Instantaneous Band Gap Collapse in Photoexcited Monoclinic VO2 Due to Photocarrier Doping / Wegkamp, D.; Herzog, M.; Xian, L.; Gatti, M.; Cudazzo, P.; Mcgahan, C. L.; Marvel, R. E.; Haglund, R. F.; Rubio, A.; Wolf, M.; Stahler, J.. - In: PHYSICAL REVIEW LETTERS. - ISSN 0031-9007. - 113:21(2014), pp. 216401-1-216401-5. [10.1103/PhysRevLett.113.216401]

Instantaneous Band Gap Collapse in Photoexcited Monoclinic VO2 Due to Photocarrier Doping

Gatti M.;Cudazzo P.;
2014-01-01

Abstract

Using femtosecond time-resolved photoelectron spectroscopy we demonstrate that photoexcitation transforms monoclinic VO2 quasi-instantaneously into a metal. Thereby, we exclude an 80 fs structural bottleneck for the photoinduced electronic phase transition of VO2. First-principles many-body perturbation theory calculations reveal a high sensitivity of the VO2 band gap to variations of the dynamically screened Coulomb interaction, supporting a fully electronically driven isostructural insulator-to-metal transition. We thus conclude that the ultrafast band structure renormalization is caused by photoexcitation of carriers from localized V 3d valence states, strongly changing the screening before significant hot-carrier relaxation or ionic motion has occurred.
2014
21
Wegkamp, D.; Herzog, M.; Xian, L.; Gatti, M.; Cudazzo, P.; Mcgahan, C. L.; Marvel, R. E.; Haglund, R. F.; Rubio, A.; Wolf, M.; Stahler, J.
Instantaneous Band Gap Collapse in Photoexcited Monoclinic VO2 Due to Photocarrier Doping / Wegkamp, D.; Herzog, M.; Xian, L.; Gatti, M.; Cudazzo, P.; Mcgahan, C. L.; Marvel, R. E.; Haglund, R. F.; Rubio, A.; Wolf, M.; Stahler, J.. - In: PHYSICAL REVIEW LETTERS. - ISSN 0031-9007. - 113:21(2014), pp. 216401-1-216401-5. [10.1103/PhysRevLett.113.216401]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11572/356201
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