Magnetic flux penetration depth study in Nb/Co system

Abstract

A series of Co/Nb bilayers, Nb/Co/Nb and Co/Nb/Co trilayer thin films are made by dc sputtering. Magnetic hysteresis loops are measured to study the interplay between superconductor and ferromagnet. Our results show the influence of large exchange field and small spin-orbit interaction on superconductivity. We inferred a magnetic penetration depth of ∼35–40 nm in Nb. Suppression of superconducting signal by 0.6-nm-thick Co between two 30 nm Nb films suggests confinement of the superconducting wave function within individual layers.