Abstract
Using femtosecond time-resolved photoelectron spectroscopy we demonstrate that photoexcitation transforms monoclinic quasi-instantaneously into a metal. Thereby, we exclude an 80 fs structural bottleneck for the photoinduced electronic phase transition of . First-principles many-body perturbation theory calculations reveal a high sensitivity of the 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 valence states, strongly changing the screening before significant hot-carrier relaxation or ionic motion has occurred.
- Received 15 July 2014
DOI:https://doi.org/10.1103/PhysRevLett.113.216401
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