Asymmetric anisotropic magnetoresistance in epitaxial Fe3O4 thin films

We aimed to study the effect of current orientation on the anisotropic magnetoresistance (AMR) and the planar Hall effect (PHE) in a single-crystalline Fe3O4 (001) thin film at room temperature. AMR exhibits an unusual asymmetric behavior with respect to the current direction when the current does not flow along the high symmetry crystal axes, such as the <100> or <110> directions. AMR and PHE strongly depend upon the current direction angle, θJ, with an in-plane fourfold symmetry. The amplitude and phase shift of AMR and PHE can be understood quantitatively by a phenomenological description of the anisotropic resistivity tensor in a single-crystalline system. These results prove that the current direction can be used to modify the AMR effect.