Enhanced controllable triplet proximity effect in superconducting spin-orbit coupled spin valves with modified superconductor/ferromagnet interfaces

Alex T. Bregazzi; Jabir A. Ouassou; Arthur G. Coveney; Nadia A. Stelmashenko; Ali Child; Alpha T. N'Diaye; Jason W. A. Robinson; Fasil K. Dejene; Jacob Linder; Niladri Banerjee

doi:10.1063/5.0209305

arXiv · 2404.12950

Enhanced controllable triplet proximity effect in superconducting spin-orbit coupled spin valves with modified superconductor/ferromagnet interfaces

Alex T. Bregazzi·Jabir A. Ouassou·Arthur G. Coveney·Nadia A. Stelmashenko·Ali Child·Alpha T. N'Diaye·Jason W. A. Robinson·Fasil K. Dejene·Jacob Linder·Niladri Banerjee

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Abstract

In a superconductor/ferromagnet hybrid, a magnetically controlled singlet-to-triplet Cooper pair conversion can modulate the superconducting critical temperature. In these triplet superconducting spin valves, such control usually requires inhomogeneous magnetism. However, in the presence of spin-orbit coupling from an interfacial heavy-metal layer, the singlet/triplet conversion rate and thus the critical temperature, can be controlled via the magnetization direction of a single homogeneous ferromagnet. Here, we report significantly enhanced controllable pair conversion to a triplet state in a Nb/Pt/Co/Pt superconducting spin valve in which Pt/Co/Pt is homogeneously magnetized and proximity-coupled to a superconducting layer of Nb. The Co/Pt interface furthest away from Nb is modified by a sub-nanometer-thick layer of Cu or Au. We argue that the enhancement is most likely associated from an improvement of the Co/Pt interface due to the insertion of Cu and Au layers. Additionally, the higher normalized orbital moments in Au measured using X-ray magnetic circular dichroism shows that increasing spin-orbit coupling enhances the triplet proximity effect - an observation supported by our theoretical calculations. Our results provide a pathway to enhancing triplet pair creation by interface engineering for device development in superspintronics.

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Alex T. Bregazzi, Jabir A. Ouassou, Arthur G. Coveney, Nadia A. Stelmashenko, Ali Child, Alpha T. N'Diaye, Jason W. A. Robinson, Fasil K. Dejene, Jacob Linder, Niladri Banerjee. 2024-04-19. Enhanced controllable triplet proximity effect in superconducting spin-orbit coupled spin valves with modified superconductor/ferromagnet interfaces. https://doi.org/10.1063/5.0209305

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