Berry curvature dipole generation and nonreciprocal spin photocurrents in ferroelectricity polarized heterostructures

Berry curvature dipole (BCD) describes the dipole-like distribution of Berry curvature in momentum space and plays a key role for quantum geometric phenomena in nonlinear optoelectronics. Experimentally, BCD can be generated at artificially designed semiconductor heterointerfaces where rotational symmetry breaking is induced by interfacial lattice mismatch. Such a local interface symmetry breaking strategy is largely limited to the monolayer regime; however, how to induce BCD in thicker semiconductors remains challenging. Here, we demonstrate a strategy for BCD generation in semiconductors beyond the monolayer limit via ferroelectric-polarization-driven symmetry breaking in WSe₂/LiNbO₃ heterostructures. In contrast to the absence of circular galvanic photocurrent under normal incidence due to the C₃ symmetry in WSe₂, the in-plane polarization of LiNbO₃ in heterostructures breaks the C₃ symmetry of WSe₂ multilayers into C_s or C₁, and induces pronounced circular galvanic photocurrents therein. Importantly, such galvanic photocurrent is nonreciprocal to bias voltage with a giant asymmetry factor of 12. First-principles calculations reveal that the symmetry breaking and energy band reconstruction in multilayer WSe₂ induced by polarization field gives rise to a strongly-anisotropic Berry curvature distribution and further generates BCD. Our results on ferroelectricity-driven BCD provide a strategy for engineering quantum geometry in nonlinear optoelectronic devices.