Strong Structural and Property Anisotropy in CeO₂-NiFe Hybrid Metamaterials Toward Self-Assembled Magnon...

Ni₈₀Fe₂₀ (NiFe) is a well-studied conducting ferromagnet with spin-transfer torque and current-driven domain wall motion demonstrated and thus is considered as a potential candidate for magnonics and energy-efficient computational devices. Various NiFe-based nanowire and nanotube structures have been made via lithography patterning methods for magnonics demonstration. In this work, through the concept of self-assembled vertically aligned nanocomposite (VANs) thin films, vertically aligned NiFe (80:20) nanopillars are uniformly grown into an insulating dielectric oxide matrix (CeO₂) as a hybrid metamaterial framework for nanoscale magnonics demonstration. The NiFe-CeO₂ VAN system is compared with a single layer NiFe film based on film morphologies, magnetic anisotropy, and ferromagnetic resonance (FMR) properties. Because of the unique out-of-plane (OOP) alignment of the NiFe nanopillars, strong OOP anisotropy and OOP FMR properties are achieved in the NiFe-CeO₂ VAN system. This NiFe-based hybrid metamaterial framework presents as a viable alternative materials solution toward nanoscale magnon applications.