Ab initio magnetoresistance in magnetic domain walls

The effect of magnetic domain walls on the resistance of a ferromagnet is an open problem in the sense that a consistent picture concerning the magnitude and the microscopic origin is still lacking. In this paper we present ab initio calculations of the specular transmission through domain walls in nickel, cobalt and iron. We show that for domain walls with realistic thicknesses, the effect of the domain wall on the conductance (as measured in a point-contact geometry) is indeed small but non-vanishing, in agreement with the recent experiments of Gregg et al. [Phys. Rev. Lett. 77 (1996) 1580]. The change in the conductance due to the domain wall is entirely attributable to the change in the electronic band structure of the ferromagnet brought about by the magnetization rotation. For a given total rotation (e.g. a 180° wall), a strong increase with decreasing wall thickness is predicted.