Ferromagnetic Resonance in Permalloy film - Platinum/Cobalt Island Hybrid Systems*

Nanomagnetic arrays in frustrated geometries, also known as artificial spin ice (ASI), have emerged both
as a platform to study fundamental phenomena, such as emergent magnetic monopoles, and as a
potential tool to develop magnon-based quantum spintronics. One particularly interesting ASI is a hybrid
system composed of Pt/Co islands with perpendicular magnetic anisotropy coupled with a permalloy
(Py) film that acts as a flux channeling layer. This increases the coupling strength between the
nanomagnets, resulting in a strongly interacting Ising ASI [Kempinger et al., in preparation]. Here, we
characterize the dynamics of this hybrid Ising ASI via optically detected ferromagnetic resonance
(ODFMR) probed using nitrogen-vacancy (NV) center magnetometry. The highly localized
nature of the NV ODMFR measurements allows us to probe magnonic modes in individual submicron-
scale lattices on a single chip, even when the sizes of the islands are well below the diffraction limit. We
use micromagnetic simulations to identify FMR modes associated with the Py underlayer, the ASI, and
the hybrid Py-ASI system.