Spin-Orbit-Induced Magnetic Anisotropy for Impurities in Metallic Samples II. Finite Size Dependence in the Kondo Resistivity

TL;DR

This paper models how surface-induced spin-orbit anisotropy affects the Kondo resistivity in thin metallic films, explaining size-dependent experimental observations.

Contribution

It introduces a theoretical framework incorporating surface anisotropy into Kondo resistivity calculations for thin films.

Findings

Resistivity increase is suppressed near surfaces due to anisotropy.

The Kondo temperature remains approximately unchanged.

The model explains proximity effects observed experimentally.

Abstract

The electrical resistivity including the Kondo resistivity increase at low temperature is calculated for thin films of dilute magnetic alloys. Assuming that in the non-magnetic host the spin-orbit interaction is strong like in Au and Cu, the magnetic impurities have a surface anisotropy calculated in part I. That anisotropy hinders the motion of the spin. Including that anisotropy the effective electron-impurity coupling is calculated by using the second order renormalization group equations. The amplitude of the Kondo resistivity contribution is reduced as the position of the impurity approaches the surface but the increase occurs approximately at the bulk Kondo temperature. Different proximity effects observed by Giordano are also explained qualitatively where the films of magnetic alloys are covered by pure second films with different mean free path. The theory explains the experimental results in those cases where a considerable amount of impurities is at the surface inside the ballistic region.