First-principle Studies of Flexoelectric Effect in Corrugated Two-dimensional Materials

The flexoelectricity, electrical polarization induced by a strain gradient, is one of the very exotic physical phenomena because it can induce the huge piezoelectricity even in centrosymmetric materials. Here, combining density functional theory calculation and mathematical analysis, we find that the corrugation generates the great out-of-plane polarization mediated by the flexoelectric effect even in centrosymmetric two-dimensional materials. The flexoelectricity in 2D materials is highly sensitive to the corrugation strength and tunable by adjusting the curvature at the nm scale. The correlation between curvature, flexoelectricity and resulting out of plane polarization will be discussed and associated underlying mechanisms will be introduced in detail.