Bias-induced local heating in atom-sized metal contacts at 77 K

Local heating in Zn atom-sized contacts is studied at 77 K under high biases. Switching rate nu of two-level fluctuations of the contact conductance is measured and statistically analyzed to estimate the contact effective temperature. Typical log nu increases linearly with the bias up to 0.35 V, which suggests negligible contact heating in the low-bias regime. Above 0.4 V, however, log nu rises steeply with the bias due to an onset of contact overheating. The estimated contact temperature rises more rapidly with the bias than the root V dependence derived theoretically. (c) 2007 American Institute of Physics.