Kondo Effect in Systems with Spin Disorder

TL;DR

This paper investigates how static spin disorder affects the Kondo effect, deriving the distribution of impurity energy splittings and analyzing their impact on conductance and zero-bias anomalies in nanostructures.

Contribution

It introduces a method to derive the distribution functions of disorder-induced splittings in Kondo models and applies this to interpret experimental zero-bias anomalies.

Findings

Distribution functions are strongly asymmetric with smaller typical splittings.

Temperature dependence of conductance is influenced by the derived distribution.

Supports the two-channel Kondo explanation for zero-bias anomalies in nanoconstrictions.

Abstract

We consider the role of static disorder in the spin sector of the one- and two-channel Kondo models. The distribution functions of the disorder-induced effective energy splitting between the two levels of the Kondo impurity are derived to the lowest order in the concentration of static scatterers. It is demonstrated that the distribution functions are strongly asymmetric, with the typical splitting being parametrically smaller than the average rms value. We employ the derived distribution function of splittings to study the temperature dependence of the low-temperature conductance of a sample containing an ensemble of two-channel Kondo impurities. The results are used to analyze the consistency of the two-channel Kondo interpretation of the zero-bias anomalies observed in Cu/(Si:N)/Cu nanoconstrictions.