  We investigate the spin Hall magnetoresistance (SMR) at room temperature in
thin film heterostructures of antiferromagnetic, insulating, (0001)-oriented
alpha-Fe2O3 (hematite) and Pt. We measure their longitudinal and transverse
resistivities while rotating an applied magnetic field of up to 17T 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 Neel 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 alpha-Fe2O3/Pt system
particularly interesting for room-temperature antiferromagnetic spintronic
applications.
