Spin pumping blocked by single-layer graphene

Abstract

We demonstrate that spin pumping in a Ni 81 Fe 19 /Pt bilayer is strongly suppressed by inserting single-layer graphene (SLG) at the interface. Spin pumping in the Ni 81 Fe 19 /Pt bilayer enhances the magnetization damping of the ferromagnetic layer, which is quantified from the microwave frequency dependence of the ferromagnetic resonance linewidth. We show that the enhancement of the magnetization damping due to spin pumping disappears in a Ni 81 Fe 19 /SLG/Pt trilayer. This result indicates that spin pumping is blocked by the atomic monolayer, illustrating the crucial role of interfacial short-range spin-exchange coupling in spin pumping in metallic systems.

Extrinsic Surface Magnetic Anisotropy Contribution in Pt/Y3Fe5O12Interface in Longitudinal Spin Seebeck Effect by Graphene Interlayer

“…As discussed above, measured V LSSE originates from J s, which is generated in the YIG layer. Injected J s from the YIG layer can be expressed as , where g ↑↓ is the spin mixing conductance, and m is the magnetization unit vector. Thus, spin mixing conductance and magnetization have important influence on J s transport from the ferromagnetic layer (e.g., YIG) to the detection layer (e.g., Pt).…”

“…Thus, spin mixing conductance and magnetization have important influence on J s transport from the ferromagnetic layer (e.g., YIG) to the detection layer (e.g., Pt). Pt/GR/YIG structures have smaller reported g ↑↓ than Pt/YIG structures, implying that graphene interlayers block spin injection from the YIG layer. ,, Park et al, for example, reported that g ↑↓ reduced from ∼6.12 × 10 17 to ∼1.09 × 10 17 m –2 by inserting SL-GR between Pt and YIG. This g ↑↓ reduction for Pt/GR/YIG continues with increasing GR thickness because spin pumping exponentially decays with increasing barrier thickness in the Pt/barrier/YIG trilayer…”