Anomalous temperature dependence of the dephasing time in mesoscopic Kondo wires

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.

4 pages, 5 figures. Phys. Rev. Lett., in press