Photoinduced collective mode, inhomogeneity, and melting in a charge-order system

Abstract

We theoretically investigate photoresponses of a correlated electron system upon stimuli of a pulsed laser light. Real-time dynamics of an interacting spinless fermion model on a one-dimensional chain, as a model of charge order (CO), are numerically simulated using the time-dependent Hartree-Fock method. In particular, we discuss the differences between two situations as the initial state: the homogeneous order and the presence of a domain wall, i.e., a kink structure embedded in the CO bulk. Coherent dynamics are seen in the former case: When the frequency of the pump light ${\ensuremath{\omega}}_{p}$ is varied, along with single particle excitations across the CO gap (${\mathrm{\ensuremath{\Delta}}}_{\mathrm{CO}}$), the resonantly-excited collective phase mode near ${\ensuremath{\omega}}_{p}\ensuremath{\simeq}{\mathrm{\ensuremath{\Delta}}}_{\mathrm{CO}}/2$ efficiently destabilizes CO. In clear contrast, in the latter case, when ${\ensuremath{\omega}}_{p}$ is tuned at such in-gap frequencies and the intensity of light is sufficiently large, inhomogeneity spreads out from the kink to the bulk region through kink creations. Moreover, even stronger intensity induces the inhomogeneous melting of CO where the CO gap is destroyed.