Absence of Significant Spin-Current Generation in Ti/Fe-Co-B Bilayers with Strong Interfacial Spin-Orbit Coupling

After one decade of intensive theoretical and experimental explorations, whether interfacial spin-orbit coupling (ISOC) at metallic magnetic interfaces can effectively generate a spin current has remained in dispute. Here, utilizing the Ti/Fe-Co-B bilayers that are unique for the negligible bulk spin Hall effect and the strong tunable ISOC, we establish that there is no significant charge-to-spin conversion at magnetic interfaces via spin-orbit filtering effect or Rashba-Edelstein(-like) effect even when the ISOC is stronger than that of a typical Pt/ferromagnet interface and can promote strong perpendicular magnetic anisotropy. We also find a minimal orbital Hall effect in 3d Ti.

Automated summary

After a decade of intensive theoretical and experimental explorations, it remains in dispute whether interfacial spin-orbit coupling at metallic magnetic interfaces can effectively generate a spin current. Utilizing Ti/Fe-Co-B bilayers with unique properties, the study found no significant charge-to-spin conversion at magnetic interfaces, even with stronger ISOC than a typical Pt/ferromagnet interface. Additionally, a minimal orbital Hall effect was observed in 3d Ti.