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Journal Article

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

MPS-Authors
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Wegkamp,  Daniel
Physical Chemistry, Fritz Haber Institute, Max Planck Society;

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Herzog,  Marc
Physical Chemistry, Fritz Haber Institute, Max Planck Society;

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Rubio,  Angel
Nano-Bio Spectroscopy group, Universidad del País Vasco CFM CSIC-UPV/EHU-MPC & DIPC;
Theory, Fritz Haber Institute, Max Planck Society;
European Theoretical Spectroscopy Facility (ETSF);
Max Planck Institute for the Structure and Dynamics of Matter;

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Wolf,  Martin
Physical Chemistry, Fritz Haber Institute, Max Planck Society;

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Stähler,  Julia
Physical Chemistry, Fritz Haber Institute, Max Planck Society;

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Fulltext (public)

Wegkamp VO2 PRL 2014.pdf
(Publisher version), 404KB

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Citation

Wegkamp, D., Herzog, M., Xian, L., Gatti, M., Cudazzo, P., McGahan, C. L., et al. (2014). Instantaneous Band Gap Collapse in Photoexcited Monoclinic VO2 due to Photocarrier Doping. Physical Review Letters, 113(21): 216401. doi:10.1103/PhysRevLett.113.216401.


Cite as: http://hdl.handle.net/11858/00-001M-0000-0024-3F4F-D
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.