Long-distance spin transport through a graphene quantum Hall antiferromagnet

Because of their ultrafast intrinsic dynamics and robustness against stray fields, antiferromagnetic insulators(1-3) are promising candidates for spintronic components. Therefore, long-distance, low-dissipation spin transport and electrical manipulation of antiferromagnetic order are key research goals in antiferromagnetic spintronics. Here, we report experimental evidence of robust spin transport through an antiferromagnetic insulator, in our case the gate-controlled state that appears in charge-neutral graphene in a magnetic field(4-6). Utilizing quantum Hall edge states as spin-dependent injectors and detectors, we observe large, non-local electrical signals across charge-neutral channels that are up to 5 mu m long. The dependence of the signal on magnetic field, temperature and filling factor is consistent with spin superfluidity(1,2,4,7-10) as the spin-transport mechanism. This work demonstrates the utility of graphene in the quantum Hall regime as a powerful model system for fundamental studies in antiferromagnetic spintronics.