Anomalous temperature dependence of the dephasing time in mesoscopic Kondo wires

Félicien Schopfer (1) , Christopher Bäuerle (1) , Wilfried Rabaud (1) , Laurent Saminadayar (1)

1 CRTBT - Centre de Recherches sur les Très Basses Températures

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.

Domaines: Systèmes mésoscopiques et effet Hall quantique [cond-mat.mes-hall]

Félicien Schopfer, Christopher Bäuerle, Wilfried Rabaud, Laurent Saminadayar. Anomalous temperature dependence of the dephasing time in mesoscopic Kondo wires. Physical Review Letters, 2003, 90, pp.056801. ⟨hal-00114887⟩