At the end of the second paragraph of the right column on page 4 of section 2, there is a typographical error. Specifically, '… area = 0.5 × 0.5 − 30 × 30 m…' should be replaced with '…area = 0.5 × 0.5 − 30 × 30 μm 2 …'.
Artificial (CoO-)Co/Nb/Co trilayers (TLs) are studied by means of magnetization, transport, and magnetic force microscopy measurements. By using these TLs as a model system, we provide definite means to distinguish the exchange-fields and stray-fields based magnetoresistance effects observed in relevant Ferromagnetic/Superconducting/Ferromagnetic (FM/SC/FM) structures. Accordingly, we isolate and exclusively focus on the stray-fields version, to report a complete supercurrent switch, ΔR/Rnor ≈ 100%, achieved at operating temperature T > 4.2 K. Detailed series of Co(60 nm)/Nb(dNb)/Co(60 nm) TLs are studied, in which all crucial parameters that relate to the outer Co layers and to the Nb interlayer were systematically varied to unveil the factors that motivate and/or promote the observed effect. We propose a compact model that fairly captures the underlying physics of the Co(60 nm)/Nb(dNb)/Co(60 nm) TLs studied here and can be generalized to assist understanding of the relevant processes in every kind of FM/SC/FM TLs. The presented results and accompanying model are both provocative for basic research and attractive for the design of cryogenic devices.
In ferromagnetic/superconducting (FM/SC) planar hybrids, a reentrance of the upper-critical field line Hc2(T) is observed close to Tc. The effect is generally ascribed to the so-called domain-wall superconductivity and has been theoretically explored in great detail. Experimental investigations are limited mostly to FM/SC bilayers in which the FM layers host out-of-plane magnetic domains of strong anisotropy and large width (>300 nm), the SC layer is quite thick (>30 nm), and the external magnetic field was applied normal. To expand our knowledge to until now unexplored conditions, we study a series of Co(dCo)/Nb(dNb)/Co(dCo) trilayers under a parallel magnetic field; Co outer layers exhibit out-of-plane magnetic domains of weak anisotropy and small width (<150 nm) and the Nb interlayer is very thin (<20 nm). We demonstrate a strong reentrance of Hc2(T) that can be tuned through the irreversible magnetization processes of the FM outer layers, the two-dimensional character of the SC interlayer, and the matching between the interfering SC and FM length scales. These results refine the nature of the reentrance of Hc2(T) in FM/SC hybrids and can motivate new theoretical and experimental investigations.
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