Evidence for crossed andreev reflection in (100)YBa2Cu 3O7-δ-SrRuO3 superconductor-ferromagnet bilayers

Oded Millo*, Itay Asulin, Ofer Yuli, Gad Koren

*Corresponding author for this work

Research output: Contribution to journalConference articlepeer-review


Since the ferromagnetic side of a superconductor-ferromagnet junction is spin polarized, Andreev reflections are suppressed. Consequently, the induced superconductor order parameter in the ferromagnet is expected to decay rapidly, on the order of a few nm. Our scanning tunneling spectroscopy measurements on thin epitaxial (100)YBa2Cu3O7-δ SrRuO3 (YBCO-SRO) bilayers, where SRO is a ferromagnet, indeed show that on most of the junction area the superconductor order parameter vanishes in the SRO over a distance less than 8 nm. However, we find localized regions, arranged along narrow (<10 nm) stripes, where the order parameter (superconductor-like gap structure) penetrates the ferromagnet more than 20 nm. This is attributed to "crossed Andreev reflections", taking place at domain boundaries, where an electron from one magnetic domain is retro reflected as a hole with opposite spin in an adjacent domain. This phenomenon, directly observed here for the first time, may account for the (not abundant) cases where a long-range proximity effect was found in superconductor-ferromagnet proximity systems.

Original languageAmerican English
Article number593216
Pages (from-to)1-8
Number of pages8
JournalProceedings of SPIE - The International Society for Optical Engineering
StatePublished - 2005
EventStrongly Correlated Electron Materials: Physics and Nanoengineering - San Diego, CA, United States
Duration: 31 Jul 20054 Aug 2005


  • Andreev reflection
  • Ferromagnetic superconductors
  • Scanning tunneling spectroscopy
  • Superconductor proximity effect
  • YBCO


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