Nonequilibrium dynamics of suppression, revival, and loss of charge order in a laser pumped electron-phonon system

TL;DR

This paper investigates how laser pulses affect charge order in an electron-phonon system, revealing complex dynamics, multiple timescales, and transitions between insulating and metallic states in nonequilibrium conditions.

Contribution

It provides a comprehensive analysis of charge order dynamics under laser excitation, including characterization of decay, revival, and loss, and explores effective thermal descriptions and phase transitions.

Findings

Weak pulses cause low amplitude oscillations with slow decay.

Strong pulses destroy charge order rapidly with oscillatory decay.

Intermediate pulses lead to complex dynamics with multiple timescales and phase transitions.

Abstract

An electron-phonon system at commensurate filling often displays charge order (CO) in the ground state. Such a system subject to a laser pulse shows a wide variety of behaviour. A weak pulse sets up low amplitude oscillations in the order parameter, with slow decay to a slightly suppressed value. A strong pulse leads to the destruction of the charge order with the order parameter showing rapid, oscillatory, decay to zero. The regime in between, separating the weak pulse CO sustained state from the strong pulse CO destroyed state, shows complex dynamics characterised by multiple, pulse strength dependent, time scales. It involves an initial rapid decay of the order parameter, followed by a low amplitude quiescent state, and the power-law rise to a steady-state over a timescale $\tau_{cr}$. We provide a complete characterisation of the dynamics in this nonequilibrium problem for varying electron-phonon coupling and pulse strength, examine the possibility of an effective "thermal" description of the long time state, and present results on the multiple insulator-metal transitions that show up.