Evidence for Crossed Andreev Reflections in bilayers of (100)YBCO and the itinerant ferromagnet SrRuO3

TL;DR

This study provides experimental evidence of Crossed Andreev Reflections in bilayers of YBCO and SrRuO3, showing superconductor order parameter penetration over large distances near magnetic domain walls.

Contribution

It demonstrates the occurrence of Crossed Andreev Reflections in ferromagnet/superconductor bilayers, a phenomenon not previously observed in this context.

Findings

Superconductor order parameter penetrates ferromagnet over 26 nm.

Localized regions align with magnetic domain walls.

Evidence supports Crossed Andreev Reflections near domain walls.

Abstract

Scanning tunneling spectroscopy measurements on thin epitaxial SrRuO3/(100)YBCO 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. We attributed this behavior to Crossed Andreev Reflections, taking place in the vicinity of the magnetic domain walls.