Ultrafast Carrier Dynamics in VO$_2$ across the Pressure-Induced Insulator-to-Metal Transition

TL;DR

This study uses ultrafast spectroscopy to explore how pressure induces an insulator-to-metal transition in VO$_2$, revealing persistent localized states and supporting a Mott-Hubbard transition mechanism.

Contribution

It provides new insights into the ultrafast electronic dynamics and localized states in VO$_2$ during pressure-induced phase transition.

Findings

Observation of pump-probe signals in metallic state

Detection of localized electronic states under pressure

Evidence supporting bandwidth-controlled Mott-Hubbard transition

Abstract

We utilize near-infrared pump and mid-infrared probe spectroscopy to investigate the ultrafast electronic response of pressurized VO$_2$. Distinct pump-probe signals and a pumping threshold behavior are observed even in the pressure-induced metallic state showing a noticeable amount of localized electronic states. Our results are consistent with a scenario of a bandwidth-controlled Mott-Hubbard transition.