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