N.C.S.R. "Demokritos"

Research

Department of Materials Science

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Nano-hybrids constituting of superconducting and ferromagnetic ingredients

In this research activity we study the interplay of superconductivity with ferromagnetism in hybrids of nanoparticles and layered forms by examining both basic physics, such as pairing of superconducting electrons, and possible applications, such as magnetic field sensor devices. For instance, it is generally believed that superconductivity (SC) and ferromagnetism (FM) are two antagonist phenomena. Accordingly, theoretical models propose that in FM-SC-FM trilayers (TLs) the transport properties of the SC interlayer can be controlled by the in-plane relative magnetization of the outer FM layers. These models suggest that SC should be enhanced for the antiparallel in-plane magnetization configuration when compared to the parallel one as is presented in Fig. 1. Our experimental data on exchanged biased NiFe-Nb-NiFe TLs reveal the opposite behavior; SC is enhanced for the parallel “in-plane” magnetization configuration of the outer FMs as is presented in Figs. 2(a)-2(c). These results imply either a spin-triplet pairing of Cooper pairs (scenario (I) in Fig. 3) or control of SC by the out-of-plane rotation of the outer FMs’ magnetization (scenario (II) in Fig.4) as is actually revealed by the magnetization data on the transverse magnetic component shown in Fig. 2(d).

Department of Materials Science, N.C.S.R. "Demokritos", 153 10 Aghia Paraskevi, Attiki, phone: +30 210 6503381, fax: +30 210 6519430
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