Nucleation Field of a Thin Superconducting Film on a Thick Normal Layer

The nucleation field H-o of a normal-superconducting double layer is calculated when the normal layer is thick and the thickness of the superconducting film is varied and is of the order of magnitude of the coherence length in the superconducting metal. The results are general and are exact when the transition temperatures of the two metals are not too different. The above theory is extended to metal layers having very different transition temperatures. When both metal layers are thick the agreement with experiments by Eischer and Klein on lead-copper films is good.