Magnetoresistance, Micromagnetism, and Domain Wall Scattering in Epitaxial hcp Co Films

TL;DR

This study investigates the origin of large negative magnetoresistance in epitaxial hcp Co films, revealing that ferromagnetic resistivity anisotropy, rather than domain wall scattering, is the primary cause.

Contribution

The paper combines MR measurements, magnetic force microscopy, and micromagnetic calculations to clarify the dominant mechanism behind magnetoresistance in Co films.

Findings

Large negative MR is mainly due to resistivity anisotropy.

Domain wall scattering has a minimal effect on MR.

Temperature-dependent resistivity measurements support the anisotropy explanation.

Abstract

Large negative magnetoresistance (MR) observed in transport measurements of hcp Co films with stripe domains were recently reported and interpreted in terms of a novel domain wall (DW) scattering mechanism. Here detailed MR measurements, magnetic force microscopy, and micromagnetic calculations are combined to elucidate the origin of MR in this material. The large negative room temperature MR reported previously is shown to be due to ferromagnetic resistivity anisotropy. Measurements of the resistivity for currents parallel (CIW) and perpendicular to DWs (CPW) have been conducted as a function of temperature. Low temperature results show that any intrinsic effect of DWs scattering on MR of this material is very small compared to the anisotropic MR.