Anomalous temperature dependence of the dephasing time in mesoscopic Kondo wires

TL;DR

This study investigates how magnetic impurities affect electron dephasing in mesoscopic gold wires, revealing an unexpected temperature dependence linked to the Kondo effect and spin glass formation.

Contribution

It provides experimental evidence of anomalous dephasing behavior in Kondo wires, highlighting the role of spin glass formation in phase coherence at low temperatures.

Findings

Dephasing rate shows a plateau between 300 mK and 800 mK.

Below the Kondo temperature, dephasing rate decreases linearly with temperature.

Spin glass formation likely causes the anomalous temperature dependence.

Abstract

We present measurements of the magnetoconductance of long and narrow quasi one-dimensional gold wires containing magnetic iron impurities in a temperature range extending from $15 $mK to $4.2 $K. The dephasing rate extracted from the weak antilocalisation shows a pronounced plateau in a temperature region of $300 $mK - $800 $mK, associated with the phase breaking due to the Kondo effect. Below the Kondo temperature the dephasing rate decreases linearly with temperature, in contradiction with standard Fermi-liquid theory. Our data suggest that the formation of a spin glass due to the interactions between the magnetic moments are responsible for the observed anomalous temperature dependence.