Tuning Spin Transport in a Graphene Antiferromagnetic Insulator

Abstract

Long-distance spin transport through antiferromagnetic insulators (AFMIs) is a long-standing goal of spintronics research. Unlike conventional spintronics systems, monolayer graphene in the quantum Hall regime (QH) offers an unprecedented tuneability of spin-polarization and charge-carrier density in QH edge states. Here, using gate-controlled QH edges as spin-dependent injectors and detectors in an all-graphene electrical circuit, we demonstrate a selective tuning of ambipolar spin transport through graphene \ensuremath{\nu} = 0 AFMIs. By modulating polarities of the excitation bias, magnetic fields, and charge carriers that host opposite chiralities, we show that the difference between spin chemical potentials of adjacent edge channels in the spin-injector region is crucial in tuning spin transport observed across graphene AFMI. We demonstrate that nonlocal response vanishes upon reversing directions of the co-propagating edge channels when the spin filters in our devices are no longer selective for a particular spin polarization. Our results establish a versatile set of methods to tune pure spin transport via an antiferromagnetic media and open a pathway to explore their applications for a broad field of antiferromagnetic spintronics research.