We investigate the spin Hall magnetoresistance (SMR) at room temperature in thin-film heterostructures of antiferromagnetic insulating (0001)-oriented $\alpha \text{−}{\mathrm{Fe}}_2{\mathrm{O}}_3$ (hematite) and $\mathrm{Pt}$. 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 $0.25\mathrm{\%}$ is, surprisingly, twice as high as for prototypical ferrimagnetic ${\mathrm{Y}}_3{\mathrm{Fe}}_5{\mathrm{O}}_{12}/\mathrm{Pt}$ heterostructures. The SMR effect saturates at much smaller magnetic fields than in comparable antiferromagnets, making the $\alpha \text{−}{\mathrm{Fe}}_2{\mathrm{O}}_3/\mathrm{Pt}$ system particularly interesting for room-temperature antiferromagnetic spintronic applications.

• Received 29 July 2019
• Revised 14 October 2019

DOI:https://doi.org/10.1103/PhysRevApplied.13.014019