Abstract
The effective local temperature of gold nanocontacts under high biases has been evaluated at 77 K by studying the two-level fluctuations (TLFs) of conductance. Upon varying bias from 0.2 to 0.6 V, TLF frequency increases exponentially while the effective contact temperature remains unchanged, which indicates negligible current-induced heating in Au nanocontacts at least up to 0.6 V at 77 K, in accordance with a theoretical model proposed by Todorov et al. [Phys. Rev. Lett. 86 (2001) 3606].