Non-local optical response of a multi-phased quantum material

TL;DR

This paper introduces a non-local optical response model for the quantum material 1T-TaS$_2$, capturing its inhomogeneous optical behavior due to competing stacking configurations, validated through experiments and offering a new probing method.

Contribution

The study develops and experimentally validates a non-local dielectric model for 1T-TaS$_2$, revealing insights into its stacking configurations and energy landscape.

Findings

Validated non-local optical response model for 1T-TaS$_2$

Identified the role of stacking configurations in optical inhomogeneity

Proposed a non-invasive technique to probe quantum material correlations

Abstract

Light-matter interaction in quantum materials presents a new paradigm as light can tip the balance between many competing quantum many-body phases to result in new phenomena. Describing the optical response of such materials requires complex models. Here, we develop a non-local model to describe the optical response of a quantum material, 1T-TaS$_2$. 1T-TaS$_2$ is a nearly commensurate charge-density-wave material at room temperature. The competing stacking configurations of the charge domains in this layered material result in significant optical inhomogeneity that necessitates a non-local dielectric function. We experimentally measure the non-local optical response of 1T-TaS$_2$ films under various illumination intensities and validate our model. The non-local parameter extracted from our measurements sheds light on the competition between the two stacking configurations of 1T-TaS$_2$. Our technique of measuring non-local optical response serves as a quick, simple, and non-invasive method to probe the energy landscape of strong correlations in many such quantum materials.