Long-Distance Spin Transport Through a Graphene Quantum Hall Antiferromagnet*

An important goal in spintronics is to establish mechanisms that minimize dissipation in the devices that are to exhibit the action of spin currents. In magnetic insulators the easy plane ordered spin currents could be carried dissipationless in the form of spin-supercurrents. Spin superfluidity transport has been theoretically predicted in a graphene quantum Hall insulator [1]. Here we report on the first experimental demonstration of the robust spin-current transport through graphene anti-ferromagnet insulator (AFMI) in the quantum Hall regime. The charge neutrality point (CNP) forms canted anti-ferromagnet (CAF) in the ground state that effectively serves as AFMI for spin currents propagation. By utilizing quantum Hall (QH) edge modes as injector, filters and detector we find large non-local signal across 5-μm long graphene CAF region. Our work demonstrates a long-distance spin transport through AFMI in graphene and shows that QH states can serve as a powerful tool for fundamental studies of ferromagnet and anti-ferromagnet spintronics.