Probing the Magnetic Order of BiFeO₃ using Spin Hall Magnetoresistance

With Néel and Curie temperatures well above room temperature, multiferroic BiFeO₃ (BFO) is an ideal candidate material for antiferromagnetic (AFM) spintronic device applications. The limited coupling of AFMs to external magnetic field perturbations challenges investigations of the magnetic domain structure. Recently, spin Hall magnetoresistance (SMR) has been used to probe the magnetic order in AFM materials such as Fe₂O₃ and NiO. Here we show that SMR can probe the magnetic order in BFO thin films. To measure SMR, a BFO/Pt heterostructure was patterned into a Hall bar, and the longitudinal and transverse resistance measured as a function of applied magnetic field. In monodomain films, we deduce the BFO spin cycloid propagation vector from the dependence of the SMR signal on spin current orientation.