Engineering the spin conversion in graphene monolayer epitaxial structures

Heavy metals (HMs) and interfaces with spin texture are employed to get a large spin-to-charge conversion¹. Graphene in proximity with those systems has been proposed as an efficient and tunable spin transport channel. We explore the role of a graphene monolayer (Grm) between Co and HM. The Co/Grm/HM stacks have been prepared on epitaxial Ir(111) structures grown on sapphire crystals, in which the spin detector (top-HM), and the spin injector (Co) are all grown in-situ under controlled conditions and present clean and sharp interfaces. We find that an intercalated Grm effectively reduced the spin current injected into the HM from the bottom Co layer. This has been observed by detecting a net reduction of the sum of the spin Seebeck and interfacial contributions due to the presence of Grm and independently from the spin Hall angle sign of the HM used².

1. Rojas-Sánchez, J. C. & Fert, A. Compared Efficiencies of Conversions between Charge and Spin Current by Spin-Orbit Interactions in Two- and Three-Dimensional Systems. Phys. Rev. Appl. 11, 054049 (2019).

2. Anadón, A. R-S, J. C. et al. Engineering the spin conversion in graphene monolayer epitaxial structures. APL Mater. 9, 061113 (2021). Invited