Magnetic flux penetration depth study in Nb/Co system

A series of Co/Nb bilayers, Nb/Co/Nb and Co/Nb/Co trilayer thin films are m ade by dc sputtering. Magnetic hysteresis loops are measured to study the i nterplay between superconductor and ferromagnet. Our results show the influ ence of large exchange field and small spin-orbit interaction on supercondu ctivity. We inferred a magnetic penetration depth of similar to 35-40 nm in Nb. Suppression of superconducting signal by 0.6-nm-thick Co between two 3 0 nm Nb films suggests confinement of the superconducting wave function wit hin individual layers. (C) 2000 American Institute of Physics. [S0021-8979( 00)33408-9].