Enhancement of charge and spin orders in a photoexcited one-dimensional strongly correlated system

By using the time-dependent Lanczos method, the nonequilibrium pro- cess of the half-filled one-dimensional extended Hubbard model, driven by a transient laser pulse, is investigated. In the case of large on-site Coulomb interactions, there are two phases separated by a first order quantum phase transition, i.e., spin-density-wave (SDW) and charge-density-wave (CDW) phases, which are characterized by algebraic decay of spin cor- relations and a long-range (staggered) charge order, respectively. When the system is subjected to the irradiation of a laser pulse, from the SDW side near the phase boundary, with proper laser frequency and strength, a sustainable charge order enhancement can be realized while local spin correlations remain. Analogously, from the CDW side, the suppression of long-range charge order is accompanied with a local spin correlation enhancement. We analyze the conditions and investigate possible mecha- nisms of the emerging order enhancements. In off-resonance region, more extended recovery of spin correlations which may come from nonlinear effect is also observed.