Band-selective Measurement of Electronic Dynamics in VO2 using Femtosecond Near Edge X-ray Absorption

TL;DR

This paper demonstrates femtosecond x-ray absorption spectroscopy to observe ultrafast electronic dynamics during the insulator-metal phase transition in VO2, utilizing tunable synchrotron radiation for element-specific measurements.

Contribution

It introduces the first use of femtosecond x-ray absorption spectroscopy with synchrotron radiation to study rapid electronic changes in VO2.

Findings

Ultrafast electronic dynamics linked to phase transition observed.

Element-specific measurements of V and O core levels performed.

Femtosecond resolution enabled direct observation of band filling processes.

Abstract

We report on the first demonstration of femtosecond xray absorption spectroscopy. Our experiments are made possible by the use of broadly tunable bending-magnet radiation from laser-sliced electron bunches within a synchrotron storage ring. We measure ultrafast electronic dynamics associated with the photo-induced insulator-metal phase transition in VO2. Symmetry and element specific xray absorption from near 500 eV V2p and O1s core levels separately measures the filling dynamics of differently hybridized V3d O2p electronic bands near the Fermi level.