Tunneling valley Hall effect induced by coherent geometric phase

We propose a geometric phase-resolved tunneling valley Hall effect based on the coherent transmission through two combined electric barriers in $\alpha -{\mathcal{T}}_3$ lattices. It is shown that the backreflected electrons at the barrier interface may acquire a valley-dependent geometric phase. The coherence of this geometric phase leads to the valley-dependent skew tunneling, which is responsible for the transverse valley current with zero net charge. We further demonstrate that this charge-neutral transverse valley Hall current can be electrically controlled by the gate voltages applied across the two combined barrier regions and is absent when the two barriers are of equal height. Our work opens a new approach to generating the valley Hall effect, suggesting potential applications for valleytronic devices.