Topological phase transitions via attosecond x-ray absorption spectroscopy

TL;DR

This paper demonstrates that attosecond x-ray absorption spectroscopy can be used to detect topological phase transitions in a Chern insulator by analyzing laser-induced dichroism spectra linked to the system's Berry structure.

Contribution

It introduces a numerical method to observe topological phase transitions using attosecond spectroscopy in out-of-equilibrium systems.

Findings

Clear spectral signatures of topological phase transition detected

Connection established between dichroism spectra and Berry curvature

Method extends attosecond spectroscopy applications to topological materials

Abstract

We present a numerical experiment that demonstrates the possibility to capture topological phase transitions via an x-ray absorption spectroscopy scheme. We consider a Chern insulator whose topological phase is tuned via a second-order hopping. We perform time-dynamics simulations of the out-of-equilibrium laser-driven electron motion that enables us to model a realistic attosecond spectroscopy scheme. In particular, we use an ultrafast scheme with a circularly polarized IR pump pulse and an attosecond x-ray probe pulse. A laser-induced dichroism-type spectrum shows a clear signature of the topological phase transition. We are able to connect these signatures with the Berry structure of the system. This work extend the applications of attosecond absorption spectroscopy to systems presenting a non-trivial topological phase.