Half-metallicity and anisotropic magnetoresistance of epitaxial Co2FeSi Heusler films

Abstract

In this paper, the anisotropic magnetoresistance (AMR) effect was investigated to check the half-metallic/non-half-metallic nature of epitaxial Co2FeSi films. The evolution of the microstructure shows that the B2 and L21-ordering of Co2FeSi films will increase with increasing annealing temperature which causes a decrease of the d-states in the down-spin channel. When Co2FeSi films are annealed at 650 °C, better B2 and L21-ordering will change the dominant s-d scattering from s↑→d↓ to s↑→d↑. The change from a non-half-metallic to a half-metallic nature of the Co2FeSi films induces a sign change of the AMR ratio from positive to negative and a small value of the Gilbert constant (α = 0.0022).