Giant Mutual Proximity Effects in Ferromagnetic/Superconducting Nanostructures

Abstract

A strong mutual influence of superconductors (S) and ferromagnetic (F) conductors in hybrid $\mathrm{F}/\mathrm{S}$ ( $\mathrm{Ni}/\mathrm{Al}$) nanostructures is observed. The proximity-induced conductance on the F side, $\ensuremath{\Delta}G$, is 2 orders of magnitude larger than that predicted by theory. A crossover from positive to negative $\ensuremath{\Delta}G$ takes place upon an increase in the $\mathrm{F}/\mathrm{S}$ interface barrier resistance. Reentrance of the superconductors to the normal state reciprocated by changes on the F side has been found in low applied magnetic fields with new peaks in the differential resistance as an effect of the saturation magnetization. An analysis has been developed providing a base for a numerical description of the system.