Kondo Effect in Electromigrated Gold Break Junctions

TL;DR

This paper reports on the observation of Kondo effects in electromigrated gold break junctions, revealing zero-bias conductance peaks and temperature-dependent behavior consistent with Kondo physics, likely originating from atomic-scale metallic grains.

Contribution

It demonstrates gate-dependent transport measurements of Kondo impurities in gold break junctions created by controlled electromigration, highlighting the formation of atomic-scale grains as the Kondo source.

Findings

30% of devices show zero-bias conductance peaks

Kondo temperatures are approximately 7K

Peak splitting in magnetic field aligns with theoretical predictions

Abstract

We present gate-dependent transport measurements of Kondo impurities in bare gold break junctions, generated with high yield using an electromigration process that is actively controlled. Thirty percent of measured devices show zero-bias conductance peaks. Temperature dependence suggests Kondo temperatures \~7K. The peak splitting in magnetic field is consistent with theoretical predictions for g=2, though in many devices the splitting is offset from 2guB by a fixed energy. The Kondo resonances observed here may be due to atomic-scale metallic grains formed during electromigration.