  Intrinsic and extrinsic valley Hall effects are predicted to emerge in
graphene systems with uniform or spatially-varying mass terms. Extrinsic
mechanisms, mediated by the valley-dependent scattering of electrons at the
Fermi surface, can be directly linked to quantum transport simulations. This is
a promising route towards more complete experimental investigation of
valleytronic phenomena in graphene, but a major obstacle is the difficulty in
applying the sublattice-dependent potentials required. Here we show that
strongly valley-dependent scattering also emerges from bilayer graphene quantum
dots, where the gap size can be easily modulated using the interlayer
potentials in dual-gated devices. Robust valley-dependent scattering and
concomitant valley currents are observed for a range of systems, and we
investigate the role of dot size, mass strength and additional potential terms.
Finally, we note that a strong valley splitting of electronic current also
emerges when a biased bilayer dot is embedded in a single layer of graphene,
but that the effect is less robust than for a bilayer host. Our findings
suggest that bilayer graphene devices with custom mass profiles provide an
excellent platform for future valleytronic exploration of two-dimensional
materials.

Mesoscale and Nanoscale Physics