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

The bias-dependence of the quantized conductance in Au nanocontacts has been measured at liquid He temperature. Awellde ®ned 1G0 peak (G0 ˆ 2e2=h is the conductance quantum unit) appears in the conductance histogram. With increasing the bias, the 1G0 peak decreases in height, while its position remains unshifted. This behavior of the 1G0 peak is just the same as that observed at room temperature [H. Yasuda, A. Sakai, Phys. Rev. B 56 (1997) 1069]. The critical bias Vbc at which the 1G0 peak disappears is 2:2 V, which is not much different from Vbc at 300 and 77 K. This weak temperature dependence of Vbc is compatible with high-current contact instability due to electromigration of contact atoms.#2001 Elsevier Science B.V. All rights reserved.