Enhancement of the Kondo temperature of magnetic impurities in metallic point contacts due to the fluctuations of the local density of states

TL;DR

This paper investigates how local density of states fluctuations in metallic point contacts significantly enhance the Kondo temperature and broaden the Kondo peak, aligning with recent experimental observations.

Contribution

It introduces a model to estimate LDOS fluctuations in nanometer-scale point contacts and shows their substantial impact on Kondo impurity dynamics.

Findings

LDOS fluctuations are strong near the orifice of small PC's

Kondo temperature can shift by several orders of magnitude due to fluctuations

LDOS fluctuations cause broadening of the Kondo peak in measurements

Abstract

The effect of local density of states (LDOS) fluctuations on the dynamics of a Kondo impurities in a small metallic point contact (PC) is studied. To estimate the spatial and energy dependent LDOS fluctuations we investigate a model PC by means of a transfer matrix formalism. For small PC's in the nanometer scale we find that near to the orifice strong LDOS fluctuations develop. These fluctuations may shift the Kondo temperature by several orders of magnitude, and result in a strong broadening of the PC Kondo peak in agreement with the results of recent measurements.