Molecular-hybridization-induced antidamping and sizeable enhanced spin-to-charge conversion in Co20Fe60B20/β -W /C60 heterostructures

The development of power-efficient spintronic devices has been a compelling need in the post-CMOS technology era. The effective tuneability of spin-orbit coupling (SOC) in the bulk and at the interfaces of hybrid material stacks is a prerequisite for scaling down the dimensions and power consumption of these devices. In this work, we demonstrate the strong chemisorption of C₆₀ (fullerene) molecules when grown on the high-SOC β -W layer. The parent Co₂₀Fe₆₀B₂₀/β -W (CFB / β -W) bilayer exhibits large spin-to-charge interconversion efficiency, which can be ascribed to the interfacial SOC observed at the ferromagnet/heavy-metal interface. Further, the adsorption of C₆₀ molecules on β -W reduces the effective Gilbert damping by ∼15 % in CFB / β -W /C₆₀ heterostructures. The antidamping is accompanied by a gigantic ∼115 % enhancement in the spin-pumping-induced output voltage owing to molecular hybridization. The noncollinear density-functional-theory calculations confirm the long-range enhancement of the SOC of β -W upon the chemisorption of C₆₀ molecules, which in turn can also enhance the SOC at the CFB / β -W interface in CFB / β -W /C₆₀ heterostructures. The combined amplification of the bulk as well as the interfacial SOC upon molecular hybridization stabilizes the antidamping and enhanced spin-to-charge conversion, which can pave the way for the fabrication of power-efficient spintronic devices.