Anomalous Hall magnetoresistance in single-crystal Fe(001) films

The angular-dependent magnetoresistance (MR) in epitaxial Fe(001) films grown on MgO(001) is systematically investigated at room temperature. The resistivities with in-plane magnetic fields parallel (ρ _x) and transverse (ρ _y) to a current and a perpendicular field (ρ _z) show a correlation of ρ _z ≈ ρ _x > ρ _y for Fe film thickness (d _Fe) between 3 and 50 nm, which is distinctly different from the conventional anisotropic MR relation of ρ _x > ρ _y ≈ ρ _z. The dependence of such unusual MR on d _Fe is quantitatively explained by the competition between the anomalous Hall MR, intrinsic anisotropic MR, and the MR induced by the geometrical size effect in Fe films. Our results also reveal the strong four-fold symmetric terms in the measured angular-dependent MR with a linear dependence of 1/d _Fe. (paper)