2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/116102We report on the experimental investigation of electronic transport in superconductor-ferromagnet spin-valve structures. Our samples consist of two ferromagnetic iron leads forming planar tunnel contacts to a superconducting aluminum wire. At energies below the superconducting gap, we observe a negative four-probe resistance that can be explained by crossed Andreev reflection.4 pages, 5 figures, revtexMesoscale and Nanoscale Physicstext