Phonon driven Floquet matter

TL;DR

This paper explores how resonantly excited coherent phonons induce non-equilibrium Floquet states in materials, revealing intricate electronic spectral features and potential for dynamical control of material properties.

Contribution

It demonstrates the application of Floquet theory to coherent lattice vibrations, showing phonon-dressed states and their spectral signatures in graphene, extending Floquet concepts beyond light-driven systems.

Findings

Phonon-dressed states exhibit complex sideband structures.

Electron-phonon coupling influences the electronic spectrum.

Floquet phases can be induced by coherent phonons in materials.

Abstract

A resonantly excited coherent phonon leads to a periodic oscillation of the atomic lattice in a crystal structure bringing the material into a non-equilibrium electronic configuration. Periodically oscillating quantum systems can be understood in terms of Floquet theory and we show these concepts can be applied to coherent lattice vibrations reflecting the underlying coupling mechanism between electrons and bosonic modes. This coupling leads to dressed quasi-particles imprinting specific signatures in the spectrum of the electronic structure. Taking graphene as a paradigmatic material we show how the phonon-dressed states display an intricate sideband structure revealing electron-phonon coupling and topological ordering. This work establishes that the recently demonstrated concept of light-induced non-equilibrium Floquet phases can also be applied when using coherent phonon modes for the dynamical control of material properties. The present results are generic for bosonic time-dependent perturbations and similar phenomena can be observed for plasmon, magnon or exciton driven materials.