Effect of spin-orbit interaction on a magnetic impurity in the vicinity of a surface

TL;DR

This paper introduces a new surface-induced magnetic anisotropy mechanism caused by spin-orbit coupling, explaining the thickness dependence of Kondo resistivity in thin magnetic alloy films.

Contribution

It proposes a novel mechanism for surface anisotropy driven by spin-orbit interaction at the impurity, with quantitative estimates matching experimental observations.

Findings

Surface anisotropy energy oscillates with impurity-surface distance

Anisotropy decays as 1/d^2 with distance from surface

Mechanism explains the magnitude of observed effects

Abstract

We propose a new mechanism for surface-induced magnetic anisotropy to explain the thickness-dependence of the Kondo resistivity of thin films of dilute magnetic alloys. The surface anisotropy energy, generated by spin-orbit coupling on the magnetic impurity itself, is an oscillating function of the distance d from the surface and decays as 1/d^2. Numerical estimates based on simple models suggest that this mechanism, unlike its alternatives, gives rise to an effect of the desired order of magnitude.