抄録
The I–V characteristics of point contacts between superconductors have been studied for their dependence on the temperature, the magnetic field and the microwave power level. Structures which appeared in the I–V characteristics in the absence of microwave powers have been related to the enhanced superconductivity of a part of the contacts and the subharmonic tunneling effects. Most of the temperature dependence of the zero-voltage current can be explained by considering the spatial variation of the current density and introducing a “mean Josephson penetration depth”. Microwave power dependence of the amplitude of induced steps disagrees with the Bessel function behavior. The discrepancy may be caused by the effect of the Josephson penetration depth.
