Negative absolute conductivity in photoexcited metals

TL;DR

This paper demonstrates that photoexcited metals can exhibit negative dc conductivity due to the interplay of electronic structure, phonon interactions, and pump intensity, with potential long-lasting non-equilibrium states.

Contribution

It provides a theoretical model showing negative conductivity in photoexcited metals, including effects of scattering and relaxation, and explores the time evolution of this state.

Findings

Negative dc conductivity can occur in photoexcited metals.

Non-equilibrium states may persist long after excitation.

Theoretical support for previously observed phenomenology.

Abstract

We show that in a model of a metal photoexcited by a transient pump pulse resonant with a phonon mode the absolute dc conductivity may become negative, depending on the interplay between the electronic structure, the phonon frequency and the pump intensity. The analysis includes the effects of inelastic scattering and thermal relaxation. Results for the time evolution of the negative conductivity state are presented; the associated non-equilibrium physics may persist for long times after the pulse. Our findings provide a theoretical justification for previously proposed phenomenology and indicate new routes to the generation and exploration of intrinsically non-equilibrium states.