Sign change of intrinsic domain wall resistance in epitaxial Heusler alloy Co2MnAl thin films

The investigation of magnetic domain wall resistance (DWR) in epitaxial Co2MnAl (CMA) thin films, a Heusler alloy, has revealed a remarkable phenomenon of sign change. This intriguing behavior is attributed to the half-metallic band structure with high spin polarization, as verified by negative anisotropic magnetoresistance in the two-current model. In this way, the scattering relaxation time for the majority and minority electrons, which is primarily determined by the density of states of majority and minority electrons, undergoes a dramatic change in the vicinity of the half-metallic band gap. This results in an unusual upturned relaxation time ratio, leading to the sign change of intrinsic DWR. These findings deepen our understanding of the intricate dynamics of spin-dependent phenomena in half metals and shed light on the entangled magnetoresistance in Heusler alloy with high spin polarization.