Sign reversal of Berry curvature across two oppositely gated regions in bilayer graphene can give rise to counter-propagating 1D channels with opposite valley indices. Previous work achieved good contrast only with an external magnetic field, limiting applications. This paper presents improved performance through optimized device geometry and stacking, showing a two-order-of-magnitude conductance difference between valley-polarized and gapped states, paving the way for zero-magnetic-field experiments.
