Orbital Hall magnetoresistance in Ni/Ti bilayers

We report the observation of the orbital counterpart of the spin Hall magnetoresistance (SMR): the orbital Hall magnetoresistance (OMR). We measured angular-dependent longitudinal magnetoresistance for Ni/Ti bilayer and Ni single-layer films by rotating a magnetic field along three orthogonal planes. When the magnetic field is rotated in the plane perpendicular to the applied current direction, the angular dependence of the magnetoresistance in the Ni/Ti bilayers is consistent with the prediction of the SMR and OMR, whereas that in the Ni single-layer film can be attributed to the geometrical size effect of the anisotropic magnetoresistance. In the Ni/Ti bilayers, the magnetoresistance ratio is found to be five orders of magnitude larger than the prediction of the SMR, indicating that the OMR plays a dominant role in this system.