Bias-dependence of the conductance of Au nanocontacts at 4 K

Abstract

The bias-dependence of the quantized conductance in Au nanocontacts has been measured at liquid He temperature. A well-defined 1 G 0 peak ( G 0=2 e 2/ h is the conductance quantum unit) appears in the conductance histogram. With increasing the bias, the 1 G 0 peak decreases in height, while its position remains unshifted. This behavior of the 1 G 0 peak is just the same as that observed at room temperature [H. Yasuda, A. Sakai, Phys. Rev. B 56 (1997) 1069]. The critical bias V bc at which the 1 G 0 peak disappears is ∼2.2 V, which is not much different from V bc at 300 and 77 K. This weak temperature dependence of V bc is compatible with high-current contact instability due to electromigration of contact atoms.