Nanoscale-femtosecond dielectric response of Mott insulators captured by two-color near-field ultrafast electron microscopy.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 33188192.
- Also identified by DOI 10.1038/s41467-020-19636-6 and PMC identifier 7666229.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Characterizing and controlling the out-of-equilibrium state of nanostructured Mott insulators hold great promises for emerging quantum technologies while providing an exciting playground for investigating fundamental physics of strongly-correlated systems. Here, we use two-color near-field ultrafast electron microscopy to photo-induce the insulator-to-metal transition in a single VO<sub>2</sub> nanowire and probe the ensuing electronic dynamics with combined nanometer-femtosecond resolution (10<sup>-21</sup> m ∙ s). We take advantage of a femtosecond temporal gating of the electron pulse mediated by an infrared laser pulse, and exploit the sensitivity of inelastic electron-light scattering to changes in the material dielectric function. By spatially mapping the near-field dynamics of an individual nanowire of VO<sub>2</sub>, we observe that ultrafast photo-doping drives the system into a metallic state on a timescale of ~150 fs without yet perturbing the crystalline lattice. Due to the high versatility and sensitivity of the electron probe, our method would allow capturing the electronic dynamics of a wide range of nanoscale materials with ultimate spatiotemporal resolution.