Light induced nonequilibrium dynamics in a charge ordering system -Role of inhomogeneity-

We theoretically study early-stage nonequilibrium dynamics of a charge ordering (CO) system as a prototypical example of strongly correlated electrons showing photo-induced phase transition (PIPT). Our aim is to reconcile two different pictures of cooperative PIPT, i.e., spatially uniform excitation by laser light irradiation vs inhomogeneous growth of domains. To investigate this problem, we consider the one-dimensional interacting spinless fermion model as a basic model for CO owing to correlation effect, and apply Hartree-Fock real-time simulation by the time-dependent Schrödinger equation. We compare two cases as the initial state before light irradiation: a uniform CO state and a one-kink state imbedded in the bulk CO. When a short laser pulse is applied to the system, in the former case, we find that the reduction of CO amplitude shows a resonant behavior for frequencies near the half of the CO gap. In clear contrast, the latter one-kink state undergoes a significantly distinct process: As time evolves, an inhomogeneous region grows because of kink generations and motions, and in some cases, results in PIPT with CO melting and destruction.