Interfacial roughness and proximity effects in superconductor/ferromagnet CuNi/Nb heterostructures

We report an investigation of the structural and electronic properties of hybrid superconductor/ferromagnet (S/F) bilayers of composition Nb/Cu60Ni40 prepared by magnetron sputtering. X-ray and neutron reflectometry show that both the overall interfacial roughness and vertical correlations of the ro...

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Bibliographic Details
Published in:Journal of applied physics 2015-12, Vol.118 (21)
Main Authors: Khaydukov, Yu, Morari, R., Soltwedel, O., Keller, T., Christiani, G., Logvenov, G., Kupriyanov, M., Sidorenko, A., Keimer, B.
Format: Article
Language:English
Subjects:
Aluminum oxide
Applied physics
Cooper pairs
Dependence
Electronic properties
Ferromagnetism
Heterostructures
Inductance
Magnetron sputtering
Reflectometry
Roughness
Silicon substrates
Superconductors
Temperature
Thickness
Transition temperature
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Summary:We report an investigation of the structural and electronic properties of hybrid superconductor/ferromagnet (S/F) bilayers of composition Nb/Cu60Ni40 prepared by magnetron sputtering. X-ray and neutron reflectometry show that both the overall interfacial roughness and vertical correlations of the roughness of different interfaces are lower for heterostructures deposited on Al2O3(11¯02) substrates than for those deposited on Si(111). Mutual inductance experiments were then used to study the influence of the interfacial roughness on the superconducting transition temperature, TC. These measurements revealed a ∼4% higher TC in heterostructures deposited on Al2O3, compared to those on Si. We attribute this effect to a higher mean-free path of electrons in the S layer, caused by a suppression of diffusive scattering at the interfaces. However, the dependence of the TC on the thickness of the ferromagnetic layer is not significantly different in the two systems, indicating a weak influence of the interfacial roughness on the transparency for Cooper pairs.
ISSN:0021-8979
1089-7550
DOI:10.1063/1.4936789