Magnetic response of a mesoscopic superconducting disk surrounded by a normal metal

Magnetic response of a superconductor/normal-metal (S/N) concentric disk is studied by use of a ballistic Hall magnetometer, which enables us to investigate the mutual proximity effects in a single and a micrometer-sized sample. The core of the sample is a type-I superconductor whose diameter is comparable to the coherence length and the magnetic penetration depth. The core and the surround are prepared by an improved double-angle evaporation method to realize their metallic contacts. At T = 1.3 K, the pair breaking effect on the S has been predominant. We have observed the smaller diamagnetic susceptibility, the larger critical field, and the less stable vortex states in the S/N sample than in only S sample. These results are attributed to the suppression of the surface superconductivity, which effectively decreases the diameter of the superconductor.