We propose a mechanism for the generation of pure superconducting spin-current carried by equal-spin triplet Cooper pairs in a superconductor (S) sandwiched between a ferromagnet (F) and a normal metal (${\mathrm{N}}_{\mathrm{so}}$) with intrinsic spin-orbit coupling. We show that in the presence of Landau Fermi liquid interactions the superconducting proximity effect can induce nonlocally a ferromagnetic exchange field in the normal layer, which disappears above the superconducting transition temperature of the structure. The internal Landau Fermi liquid exchange field leads to the onset of a spin supercurrent associated with the generation of long-range spin-triplet superconducting correlations in the trilayer. We demonstrate that the magnitude of the spin supercurrent as well as the induced magnetic order in the ${\mathrm{N}}_{\mathrm{so}}$ layer depends critically on the superconducting proximity effect between the S layer and the F and ${\mathrm{N}}_{\mathrm{so}}$ layers and the magnitude of the relevant Landau Fermi liquid interaction parameter. We investigate the effect of spin flip processes on this mechanism. Our results demonstrate the crucial role of Landau Fermi liquid interaction in combination with spin-orbit coupling for the creation of spin supercurrent in superconducting spintronics, and give a possible explanation of a recent experiment utilizing spin-pumping via ferromagnetic resonance [Jeon et al., Nat. Mater. 17, 499 (2018)].

• Received 2 August 2018

DOI:https://doi.org/10.1103/PhysRevB.98.104513