Comparison of energy and phase relaxation in metallic wires

Abstract

We have determined the phase coherence time, τφ, frommagnetoresistance measurements of long, narrow wires ofAu, Ag, and Cu, over the temperature range40 mK-6 K. In the Cu and Au wires, τφsaturates at low temperature. In the Ag wire,τφ continues to increase down to the lowesttemperatures measured; moreover, its temperature dependencebelow about 1 K is consistent with theoreticalpredictions of Altshuler, Aronov and Khmelnitskii published in1982. These results cast doubt on recent assertions thatsaturation of τφ at low temperature is a universalphenomenon in metal wires. We compare these results with thoseof recent experiments on energy relaxation in similar metallicwires. The results of the two experiments are stronglycorrelated, suggesting that a single (unknown) mechanism isthe cause of the enhanced phase and energy relaxation observedin some samples.