Theoretical study of nonlinear optical responses of non-centrosymmetric Mott insulators

Non-centrosymmetric materials host second-order nonlinear optical responses of electrons such as second harmonic generation and shift current. While formulation of these optical responses in non-interacting systems is well known and is actively studied, such formulation cannot be directly applied to systems with strong interaction effects. In this study, we investigate nonlinear optical responses in non-centrosymmetric Mott insulators, by studying the so called Rice-Mele model with Hubbard interaction by slave-rotor representation. We obtain its phase diagram and compute linear and nonlinear optical responses with a diagrammatic method.