On-Chip Ferromagnetic Resonance for van der Waals Heterostructures: Anisotropy and Damping of Cobalt Interfaced with Exfoliated 2D Materials

Designing the next generation of ultralow-power spintronic devices hinges on identifying suitable combinations of materials and interfaces that effectively process spin information. Two-dimensional (2D) materials and their associated van der Waals heterostructures offer a promising platform thanks to their ideal interfaces and exceptional tunability. However, the typical lateral dimensions of state-of-the-art exfoliated crystals are constrained to a few tens of micrometers. Addressing this limitation, we introduce a fully on-chip ferromagnetic resonance (FMR) setup optimized for these constraints. Our setup demonstrates remarkable sensitivity, capable of probing the magnetization dynamics of single cobalt (Co) patches with surfaces below 10 2 μm 2 and thicknesses in the 10 nm range at room temperature. Furthermore, the versatility of our prototype toward studying stacked van der Waals heterostructure spintronics is demonstrated by shedding light onto Co surface anisotropy and magnetic damping when proximitized by multilayer thick 2D materials such as graphene, hBN, and WSe 2 .