We have measured conductance histograms of atomic point contacts made from the noble-transition metal alloys CuNi, AgPd, and AuPt for a concentration ratio of 1:1. For all alloys these histograms at low bias voltage (below 300 mV) resemble those of the noble metals whereas at high bias (above 300 mV) they resemble those of the transition metals. We interpret this effect as a change in the composition of the point contact with bias voltage. We discuss possible explanations in terms of electromigration and differential diffusion induced by current heating.
@article{arxiv.cond-mat/0209577,
title = {A Current Induced Transition in atomic-sized contacts of metallic Alloys},
author = {Jan W. T. Heemskerk and Yves Noat and David J. Bakker and Jan M. van Ruitenbeek and Barend J. Thijsse and Peter Klaver},
journal= {arXiv preprint arXiv:cond-mat/0209577},
year = {2009}
}