Theory of magnetoresistance in films of dilute magnetic alloys

TL;DR

This paper develops a theoretical model for magnetoresistance in dilute magnetic alloy films, incorporating surface-induced magnetic anisotropy, and compares it with experimental data on Au(Fe) films of varying thickness.

Contribution

It introduces a detailed theoretical calculation of magnetoresistance considering surface anisotropy, validated against recent experimental measurements.

Findings

Magnetic anisotropy exists near surfaces of dilute magnetic alloys.

The calculated field dependence matches experimental observations.

Anisotropy strength aligns with previous estimates from size-dependent Kondo effects.

Abstract

Earlier a magnetic anisotropy for magnetic impurities nearby the surface of non-magnetic host was proposed in order to explain the size dependence of the Kondo effect in dilute magnetic alloys. Recently Giordano has measured the magnetoresistance of dilute Au(Fe) films for different thicknesses well above the Kondo temperature $T_K$. In this way he verified the existence of that anisotropy even for such a case where the Kondo effect is not dominating. For detailed comparison of that suggestion with experiments, the magnetic field dependence of the magnetoresistance is calculated in the lowest approximation, thus in the second order of the exchange coupling. The strength of the anisotropy is very close to earlier estimates deduced from the size dependence of the Kondo resistivity amplitude.