Tunable pure spin supercurrents and the demonstration of their gateability in a spin-wave device
Kun-Rok Jeon, X. Montiel, Sachio Komori, Chiara Ciccarelli, Haigh, J. A. Haigh, H. Kurebayashi, L. F. Cohen, Alex K. Chan, Kilian D. Stenning, Chang-Min Lee, M. G. Blamire, Jason W. A. Robinson
Abstract
Recent ferromagnetic resonance experiments and theory of Pt/Nb/Ni8Fe2 proximity-coupled structures strongly suggest that spin-orbit coupling (SOC) in Pt in conjunction with a magnetic exchange field in Ni8Fe2 are the essential ingredients to generate a pure spin supercurrent channel in Nb. Here, by substituting Pt for a perpendicularly magnetized Pt/Co/Pt spin-sink, we are able to demonstrate the role of SOC, and show that pure spin supercurrent pumping efficiency across Nb is tunable by controlling the magnetization direction of Co. By inserting a Cu spacer with weak SOC between Nb and Pt/(Co/Pt) spin-sink, we also prove that Rashbatype SOC is key for forming and transmitting pure spin supercurrents across Nb. Finally, by engineering these properties within a single multilayer structure, we demonstrate a prototype superconductor spin-wave (SW) device in which lateral SW propagation is gateable via the opening or closing of a vertical pure spin supercurrent channel in Nb.