Berry curvature dipole generation and helicity-to-spin conversion at symmetry-mismatched heterointerfaces

Authors

Siyu Duan, Feng Qin, Peng Chen, Xupeng Yang, Caiyu Qiu, Junwei Huang, Gan Liu, Zeya Li, Xiangyu Bi, Fanhao Meng, Xiaoxiang Xi, Jie Yao, Toshiya Ideue, Biao Lian, Yoshihiro Iwasa, Hongtao Yuan

Abstract

The Berry curvature dipole (BCD) is a key parameter that describes the geometric nature of energy bands in solids. It defines the dipole-like distribution of Berry curvature in the band structure and plays a key role in emergent nonlinear phenomena. The theoretical rationale is that the BCD can be generated at certain symmetry-mismatched van der Waals heterointerfaces even though each material has no BCD in its band structure. However, experimental confirmation of such a BCD induced via breaking of the interfacial symmetry remains elusive. Here we demonstrate a universal strategy for BCD generation and observe BCD-induced gate-tunable spin-polarized photocurrent at WSe₂/SiP interfaces. Although the rotational symmetry of each material prohibits the generation of spin photocurrent under normal incidence of light, we surprisingly observe a direction-selective spin photocurrent at the WSe₂/SiP heterointerface with a twist angle of 0°, whose amplitude is electrically tunable with the BCD magnitude. Our results highlight a BCD–spin–valley correlation and provide a universal approach for engineering the geometric features of twisted heterointerfaces.

Nature Nanotechnology: https://www.nature.com/articles/s41565-023-01417-z