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

Abstract

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 .

Spin anomalous-Hall unidirectional magnetoresistance

“…For instance, both a bulk anisotropic magnetoresistance and planar Hall resistance may result from two consecutive transverse scatterings of spin-polarized conduction electrons, due to the anomalous Hall effect [3]. In geometrically confined systems-such as ferromagneticmetal thin films or layered structures, the anomalous-Hall induced anisotropic magnetoresistances may acquire distinctive angular dependences, owing to the modulation of the bulk spin and charge currents caused by interfacial spin accumulation and the resulting diffusive spin current [4][5][6][7][8][9]. * E-mail: shulei.zhang@case.edu…”