π-shifted magnetoconductance oscillations in mesoscopic superconducting-normal heterostructures

Interference of proximity-induced superconducting correlations in mesoscopic metallic rings is sensitive to the magnetic flux Phi inside these rings. This is the reason for magnetoconductance oscillations in such systems. We detected experimentally and explained theoretically a novel effect: the phase of these oscillations can switch between 0 and pi depending on the resistance of intermetallic interfaces and temperature. The effect is due to a nontrivial interplay between the proximity-induced enhancement of the local conductivity and the proximity-induced suppression of the density of states at low energies.