The Floquet Fermi Liquid

TL;DR

This paper introduces the concept of a non-equilibrium Floquet Fermi Liquid state with nested Floquet Fermi surfaces, exhibiting unique quantum oscillations and tunable properties via external drive parameters.

Contribution

It presents the theoretical prediction and characterization of Floquet Fermi Liquids with nested Fermi surfaces and their observable quantum oscillation phenomena.

Findings

Existence of Floquet Fermi Surfaces with nested structure

Quantum oscillations with slow beating patterns observed

Tunable Floquet Fermi surfaces near van-Hove singularities

Abstract

We demonstrate the existence of a non-equilibrium "Floquet Fermi Liquid" state arising in partially filled Floquet Bloch bands weakly coupled to ideal fermionic baths, which possess a collection of "Floquet Fermi surfaces" enclosed inside each other, resembling matryoshka dolls. We elucidate several properties of these states, including their quantum oscillations under magnetic fields which feature slow beating patterns of their amplitude reflecting the different areas of the Floquet Fermi surfaces, consistent with those observed in microwave induced resistance oscillation experiments. We also investigate their specific heat and thermodynamic density of states and demonstrate how by controlling properties of the drive, such as its frequency, one can tune some of the Floquet Fermi surfaces towards non-equilibrium van-Hove singularities without changing the electron density.