Probing layered magnets with graphene van der Waals heterostructures

Layered magnets are promising platforms for science and applications including novel quantum magnetic phases, nanoscale magnetic memory, and spintronics devices. However common bulk probes such as neutron and x-ray scattering or thermal probes are difficult or impossible to use to characterize these materials in the few-layer limit. We seek to develop new approaches for probing devices incorporating single-/few-layer magnets. Electronic transport in graphene can be influenced by both nearby and nonlocal scatterers. We have found that the resistance of graphene exhibits a nonmonotonic change with temperature when placed in contact with a material undergoing a magnetic phase transition. This is reminiscent of “critical resistivity” measurements in (anti-)ferromagnetic metals dating back over 50 years, which show that transport can be sensitive to spin-scattering. Motivated by these findings, we explore transport in graphene separated from layered magnets by thin hexagonal boron nitride (hBN). We find unusual nonmonotonic changes in graphene resistance persist even when the graphene is only in contact with hBN, suggesting that nearby magnetic materials impact transport. We show results for devices incorporating magnetic metals (Gd, Dy) as well as layered magnets α-RuCl3 and FePS3.