Czechoslovak journal of physics vol:46 pages:2337-2338
We have measured the magnetoresistance R(B) and the magnetic phase boundaries T-c(B) of a mesoscopic superconducting Al loop and of the leads connected to the loop. Pronounced oscillations with flux period h/2e of R(B) and T-c(B) are observed for the loop as well as for the leads. At low magnetic fields the oscillation amplitude Delta T-c(B) of the loop is suppressed when compared to the usual Little-Parks oscillations in Al microcylinders. With increasing magnetic field, Delta T-c(B) for the loop rises to the theoretically expected value, while the nonlocal oscillations in the leads are dying out. The results can be understood in terms of a proximity effect coupling between the leads and the loop, which is weakened when the temperature dependent coherence length decreases.