Evidence for Crossed Andreev Reflection in (100)YBa2Cu3O7-&#948;-SrRuO3 superconductor-ferromagnet bilayers

Oded Millo; Itay Asulin; Ofer Yuli; Gad Koren

doi:10.1117/12.621040

30 August 2005 Evidence for Crossed Andreev Reflection in (100)YBa₂Cu₃O_7-δ-SrRuO₃ superconductor-ferromagnet bilayers

Oded Millo, Itay Asulin, Ofer Yuli, Gad Koren

Proceedings Volume 5932, Strongly Correlated Electron Materials: Physics and Nanoengineering; 593216 (2005) https://doi.org/10.1117/12.621040
Event: Optics and Photonics 2005, 2005, San Diego, California, United States

Abstract

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)YBa₂Cu₃O_7-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.

Citation Download Citation

Oded Millo, Itay Asulin, Ofer Yuli, and Gad Koren "Evidence for Crossed Andreev Reflection in (100)YBa₂Cu₃O_7-δ-SrRuO₃ superconductor-ferromagnet bilayers", Proc. SPIE 5932, Strongly Correlated Electron Materials: Physics and Nanoengineering, 593216 (30 August 2005); https://doi.org/10.1117/12.621040

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