Temperature- and field-dependent quantum oscillations in superconductor—normal-metal—superconductor junctions

Fraunhofer oscillations for Josephson junctions have been studied close to the superconducting transition temperature Tc, in order to determine the changes in operating characteristics which might be expected to occur in this regime. Because the superconducting penetration depth λₛ diverges as the temperature approaches Tc, the effective area of the junction also increases. This in turn reduces the magnetic field interval of the Fraunhofer oscillations. For dₛ comparable to dₙ, the Fraunhofer period drops by about a factor of 2 as the temperature is increased from $T=0$ to Tc. A full Ic(B,T) surface has been constructed and one finds that Ic(T) curves at constant B show an oscillatory behavior near Tc. By the proper choice of variables, either B or T can be used to control the Fraunhofer interference patterns in Josephson junctions.