Scanned-probe study of spin pumping from Y₃Fe₅O₁₂ into two-dimensional materials using ferromagnetic resonance force microscopy

Driving a ferromagnet to resonance will generate spin current normal to the interface with an adjacent normal metal due to spin pumping. Spin angular momentum dissipation in normal metal will lead to increasing damping in the ferromagnet. This phenomenon is less understood in the case of the ferromagnet/two-dimensional materials interface. Graphene, the best-known two-dimensional material, has a spin diffusion length of order of 1um, making it a poor spin sink. However, there are reports of detectable spin pumping from Y₃Fe₅O₁₂ (YIG) into CVD grown graphene that is attributed to large Rashba-Edelstein effect at the YIG/Graphene interface. Here we report a study of spin pumping in YIG/graphene heterostructures using local, force detected ferromagnetic resonance (FMR). This technique can detect FMR in an area of a few microns and, therefore, enables study of exfoliated two-dimensional materials, which have better crystal quality than CVD grown materials. We discuss spin pumping in pristine graphene as well as graphene/transition metal dichalcogenide bilayers studied using scanned ferromagnetic resonance force microscopy. We will also discuss the surprising discovery of a magnetic uniaxial anisotropy induced in a thin YIG film by the transition metal dichalcogenide overlayer.