We examined the proximity effect in granular films made of Pb, a superconductor, and Ni, a ferromagnet, with various compositions. Slow decay of the critical temperature as a function of the relative volume concentration of Ni per sample was demonstrated by our measurements, followed by a saturation of Tc. Using an approximate theoretical description of our granular system in terms of a layered one, we show that our data can only be reasonably fitted by a multilayer model. This indicates the importance of the interplay between different ferromagnetic grains; when non-collinearly magnetized they should lead to triplet Cooper pairing.
@article{arxiv.1709.04760,
title = {Proximity Effect in Superconducting-Ferromagnetic Granular Structures},
author = {Hadar Greener and Victor Shelukhin and Michael Karpovski and Moshe Goldstein and Alexander Palevski},
journal= {arXiv preprint arXiv:1709.04760},
year = {2018}
}