Comparison of energy and phase relaxation in metallic wires

We have determined the phase coherence time, tau(phi), from magnetoresistance measurements of long, narrow wires of Au, Ag, and Cu, over the temperature range 40 mK-6 K. In the Cu and Au wires, tau(phi) saturates at low temperature. In the Ag wire, tau(phi) continues to increase down to the lowest temperatures measured; moreover, its temperature dependence below about 1 K is consistent with theoretical predictions of Altshuler, Aronov and Khmelnitskii published in 1982. These results cast doubt on recent assertions that saturation of tau(phi) at low temperature is a universal phenomenon in metal wires. We compare these results with those of recent experiments on energy relaxation in similar metallic wires. The results of the two experiments are strongly correlated, suggesting that a single (unknown) mechanism is the cause of the enhanced phase and energy relaxation observed in some samples.