RESISTIVE QUANTUM OSCILLATIONS IN SUPERCONDUCTING ALUMINUM MICROSTRUCTURES

Anomalous, periodic oscillations in the electrical resistance versus a pplied magnetic field have been found in aluminum ring microstructures at temperatures in the superconducting transition region. At low fiel ds the oscillations, occurring at intervals of the flux quantum phi=h/ 2e, are characterized by sharp dips in resistance versus field, on a d ecreasing background. The quantum-interference resistance variations a re explained by periodic variations in the length lambda(Q) for excess density of quasiparticles penetrating from normal-metal regions into superconducting regions of the structure. These length variations are caused by periodic variations in critical current.