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Repulsion-to-attraction transition in correlated electron systems triggered by a monocycle pulse

We study the time evolution of the Hubbard model driven by a half-cycle or monocycle pulsed electric field F(t) using the nonequilibrium dynamical mean-field theory. We find that for properly chosen pulse shapes the electron-electron interaction can be effectively and permanently switched from repulsive to attractive if there is no energy dissipation. The physics behind the interaction conversion is a nonadiabatic shift $δ$ of the population in momentum space. When $δ\simπ$, the shifted population relaxes to a negative-temperature state, which leads to the interaction switching. Due to electron correlation effects $δ$ deviates from the dynamical phase $ϕ=\int dt F(t)$, which enables the seemingly counterintuitive repulsion-to-attraction transition by a monocycle pulse with $ϕ=0$.