Spin-filter magnetic tunnel junctions of CrSBr

CrSBr is a van der Waals anti-ferromagnetic insulator with three magnetic anisotropy axes and a Neel temperature of T_N ~ 130 K, making it an excellent candidate for spintronic applications. Here, we report on the fabrication and studies of planar tunnel junctions of graphite/few-layer CrSBr/graphite, where CrSBr serves as a tunnel barrier between the graphite electrodes and the device is encapsulated by hBN. The device is made by van der Waal stacking in an argon environment as CrSBr is air-sensitive. We utilize tunneling spectroscopy to construct the magnetic phase diagram of CrSBr as a function of the applied magnetic field along the easy, hard and intermediate axes and temperature. Devices of different layer numbers are studied. We observe very large tunneling magnetoresistance (TMR) exceeding 4700% and sharp spin-flips when the external field is applied along the easy axis and smoothly canting when the field is applied along the intermediate and hard axes. The field-induced spin flips in few-layer devices show evidence of sequential layer flipping. Inelastic tunneling features appear in thin CrSBr tunnel junctions. Additionally, the tunneling magnetoresistance exhibits non-monotonic temperature dependences that are suggestive of additional magnetic phases at T < T_N.