TEMPERATURE AND MAGNETIC-FIELD DEPENDENCE OF THE INDUCED MAGNETIZATION IN MACROSCOPIC SAMPLES DUE TO THE PROXIMITY EFFECT

We have applied the Ginzburg-Landau equations to calculate the behavio r of the diamagnetism of macroscopic samples consisting of a normal me tal in contact with a superconductor. In particular, the calculation f ocuses on the temperature region above the superconductive transition temperature T-cN Of the normal metal. We have compared these calculati ons with experimental measurements of the temperature (0.006-1 K) and magnetic field (10(-9)-10(-6) T) dependence of the diamgetism for seve ral samples of Be (T(cN)similar to 23 mK) and W (T(cN)similar to 15.5 mK) in contact with the superconductor Al (T-cS= 1.18 K). The agreemen t between the predictions and measurements is quite good and confirms the approach of using the Ginzburg-Landau model to calculate the proxi mity effect in macroscopic normal systems above their superconductive transitions.