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

Yu. Khaydukov; R. Morari; O. Soltwedel; T. Keller; G. Christiani; G. Logvenov; M. Kupriyanov; A. Sidorenko; B. Keimer

doi:10.1063/1.4936789

paper

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

arXiv:1508.02223 · doi:10.1063/1.4936789

Abstract

We report an investigation of the structural and electronic properties of hybrid superconductor/ferromagnet (S/F) bilayers of composition Nb/Cu $_{60}$ Ni $_{40}$ 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 Al $_{2}$ O $_{3}$ (1 $1 ˉ$ 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, $T_{C}$ . These measurements revealed a $\sim$ 4% higher $T_{C}$ in heterostructures deposited on Al $_{2}$ O $_{3}$ , 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 $T_{C}$ 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.

8 pages, 5 figures

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

Abstract

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