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