High-frequency response of metallic point contacts with small electron mean free path
Abstract
The effect of an external electromagnetic field on metallic point contacts (copper–copper, nickel–nickel) in the thermal regime of current flow has been studied. The frequency of the electromagnetic field varied from the acoustic to the optical region. A microscopic calculation has been carried out, within the framework of point contact spectroscopic theory, of the contact response as a function of the applied bias. Results of the calculation are convincingly confirmed by the experimental results at acoustic and microwave frequencies. In the range 4.3·1012 – 28·1012 Hz a change in the bias dependence of the signal was observed. The effect is explained by the heating of the pre-contact region by the radiation. Calculations made on this assumption gave satisfactory agreement with experiment. This result agrees with the change in the mechanism of the effect of a HF field on point contacts in the ballistic regime of current flow, observed previously.