Speaker: Dr Remko Fermin, Department of Materials Science & Metallurgy, University of Cambridge

Abstract:
Generally, superconductivity and magnetism are two antagonistic processes. However, advances of the last 20 years have shown that, utilizing non-collinear magnetic layers or spin-orbit coupling, unconventional supercurrents can be generated that can penetrate ferromagnets over long length scales (so called long-range spin-triplet supercurrents). Even though the alternative generation of spin-triplet supercurrents using magnetic structures, such as domain walls and vortices, has been the subject of intense theoretical discussions, the relevant experiments remain scarce. During this talk, I will present our results on nanostructured Josephson junctions with a highly controllable spin texture, based on disk- and ellipse-shaped Nb/Co bilayers. We use the vortex magnetization of the cobalt in disk-shaped junctions to induce long-range triplet (LRT) superconductivity in the ferromagnet. Surprisingly, the LRT correlations emerge in highly localized (sub-80 nm) channels at the rim of the ferromagnet, despite its trivial band structure. We show that these robust rim currents arise from the magnetization texture acting as an effective spin–orbit coupling, which results in spin accumulation at the bilayer–vacuum boundary. Our approach, that combines micromagnetic modeling with microstructured SF-hybrids, presents a novel route towards studying effective spin-orbit coupling of magnetic textures, LRT generation and, realizing superconducting memory applications.

25 minutes plus questions unless stated otherwise (please arrive a few minutes early to start on time)