Electric field controlled valley-polarized photocurrent switch based on the circular bulk photovoltaic effect

Efficient electric manipulation of valley degrees of freedom is critical and\nchallenging for the advancement of valley-based information science and\ntechnology. We put forth an electrical scheme, based on a two-band Dirac model,\nthat can switch the fully valley-polarized photocurrent between K and K'\nvalleys using the circular bulk electro-photovoltaic effect. This is\naccomplished by applying an out-of-plane electric field to the two-dimensional\nvalley materials, which enables continuous tuning of the Berry curvature and\nits sign flip. We found that the switch of the fully valley-polarized\nphotocurrent is directly tied to the sign change of Berry curvature, which\naccompanies a topological phase transition, for instance, the quantum spin Hall\neffect and the quantum valley Hall effect. This scheme has been confirmed in\nmonolayer BiAsI2 and germanene through first-principles calculations. Our paper\noffers a promising strategy for the development of a volatile\nvalley-addressable memory device and could inspire further research in this\narea.\n