Large Spin Hall Magnetoresistance in Antiferromagnetic α-Fe2 O3/Pt Heterostructures

We investigate the spin Hall magnetoresistance (SMR) at room temperature in thin-film heterostructures of antiferromagnetic insulating (0001)-oriented α-Fe2O3 (hematite) and Pt. We measure their longitudinal and transverse resistivities while rotating an applied magnetic field of up to 17 T in three orthogonal planes. For out-of-plane magnetotransport measurements, we find indications for a multidomain antiferromagnetic configuration whenever the field is aligned along the film normal. For in-plane field rotations, we clearly observe a sinusoidal resistivity oscillation characteristic for the SMR due to a coherent rotation of the Néel vector. The maximum SMR amplitude of 0.25% is, surprisingly, twice as high as for prototypical ferrimagnetic Y3Fe5O12/Pt heterostructures. The SMR effect saturates at much smaller magnetic fields than in comparable antiferromagnets, making the α-Fe2O3/Pt system particularly interesting for room-temperature antiferromagnetic spintronic applications.