Visualization of photogenerated metallic inhomogeneity in the insulating phase of Pr$_{\bf 0.7}$Ca$_{\bf 0.3}$MnO$_{\bf 3}$ thin film using spatiotemporal terahertz radiation imaging

TL;DR

This study employs spatiotemporal terahertz radiation imaging to visualize and analyze the formation of metallic inhomogeneities in the insulating phase of a manganite thin film, revealing their dynamics and potential role in phase transition.

Contribution

The paper introduces a novel imaging technique to observe subpicosecond, micrometer-scale metallic inhomogeneities in a charge-ordered insulator, linking these to the insulator-metal transition.

Findings

Photogenerated metallic regions are created on subpicosecond timescales.

Inhomogeneity becomes homogeneous with increased laser power and bias voltage.

Photogenerated metallic regions act as nuclei for the insulator-metal transition.

Abstract

Using a spatiotemporal terahertz radiation imaging technique, we visualize photogenerated metallic inhomogeneity in the charge-ordered insulating phase of Pr$_{0.7}$Ca$_{0.3}$MnO$_3$ thin film. We reveal that photogenerated metallic regions with micrometer length scales within the charge-ordered insulating matrix are created on subpicoseond time scales. Such an inhomogeneity becomes homogeneous when the laser power and bias voltage are increased. The observed photogenerated metallic regions would act as nucleus of the insulator-metal transition observed in Pr$_{0.7}$Ca$_{0.3}$MnO$_3$.