Highly Polarized and Long Range Dissipationless Spin Transport Due to Counterflowing Electron and Hole Edge Channels

The presence of edge channels in the quantum Hall regime leads to dissipationless charge transport over long distances. When graphene is interfaced with a magnetic material, the exchange interaction lifts the Landau levels spin degeneracy. This causes the presence of counterflowing edge channels with opposite spin polarization. We show theoretically that the spin-flip scattering between these edge channels enables a dissipationless spin transport with larger than 100% spin polarization of the charge current. It also allows the transport of spin over macroscopically long distances, even in the absence of an applied charge current.