Evidence for crossed Andreev reflections in bilayers of (100) YBa2 Cu3 O7-δ and the itinerant ferromagnet SrRuO3

Scanning tunneling spectroscopy measurements on thin epitaxial SrRuO3 (100) YBa2 Cu3 O7-δ ferromagnet/superconductor bilayers, reveal localized regions in which the superconductor order parameter penetrates the ferromagnet to more than 26 nm, an order of magnitude larger than the coherence length in the ferromagnetic layer. These regions consist of narrow (<10 nm) and long strips, separated by at least 200 nm, consistent with the known magnetic domain wall structure in SrRuO3. This behavior may be due to crossed Andreev reflections, taking place in the vicinity of the magnetic domain walls.