Spin-polarised supercurrents in artificial magnetic domain walls

DIPC Seminars

J.W.A. Robinson
Donostia International Physics Center (DIPC).Paseo Manuel de Lardizabal, 4 (nearby the Facultad de Quimica), Donostia
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Spin-polarised supercurrents in artificial magnetic domain walls Supercurrents in Josephson junctions with ferromagnetic barriers are short- lived and consequently they decay within a ferromagnetic thickness of a few nanometers unless the superconductor / ferromagnet interfaces (S/F) allow spin-aligned triplet Cooper pairs to form [1]. Although much of the theoretical work describing this effect has modeled ideal S-F-S junctions in which domain walls (DWs) or DW-like structures (see, e.g., [1] and reference therein) reside at the interfaces, in real devices it is not easily possible to isolate a DW and propagate a supercurrent through it. This means that the effect of the DW structure on the supercurrent has yet to be explored experimentally. In this seminar I will present experimental results which demonstrate enhanced supercurrents, consistent with spin-triplet theory, in a variety of ferromagnetic Josephson junctions with DW-like barriers; in particular, I will discuss junctions containing synthetic antiferromagnets (Fe/Cr/Fe [2]) and rare earth spin-spirals, such as Ho [3], Ho/Co/Ho [4], and Ni/Gd/Ni [5]. [1] FS Bergeret, AF Volkov, KB Efetov, Rev. Mod. Phys. 77, 1321 (2005). [2] JWA Robinson, GB Hala?sz, AI Buzdin, MG Blamire, Phys. Rev. Lett. 104, 207001 (2010). [3] JDS Witt, JWA Robinson, MG Blamire, submitted (2012). [4] JWA Robinson, JDS Witt, MG Blamire, Science 359, 1189246 (2010). [5] JWA Robinson, F Chiodi, M Egilmez, GB Hala?sz, MG Blamire, submitted (2012).