Ultra-critical Floquet Non-Fermi Liquid

TL;DR

This paper explores how periodically driven fermionic systems coupled to bosonic baths can exhibit non-Fermi liquid behavior with sharp non-equilibrium Fermi surfaces and unique in-gap current rectification phenomena, even at finite temperatures.

Contribution

It introduces a novel non-equilibrium phase with Fermi surface singularities and universal current rectification in Floquet systems, expanding understanding beyond equilibrium physics.

Findings

Non-analyticities at certain momenta resembling Fermi surfaces.

Persistence of sharp non-equilibrium Fermi surfaces at finite temperature.

Universal in-gap current rectification in non-inversion symmetric metals.

Abstract

We demonstrate that periodically driven Fermions coupled to simple bosonic baths have steady state occupations of Floquet Bloch bands that generically display non-analyticties at certain momenta which resemble the Fermi surfaces of equilibrium non-Fermi liquids. Remarkably these non-equilibrium Fermi surfaces remain sharp even when the bath is at finite temperature, leading to critical power-law decaying correlations at finite temperature, a phenomenon with no analogue in equilibrium. We also show that generically there is in-gap current rectification for clean metals lacking inversion symmetry, and explain why this occurs universally regardless of the details of collisions.