Dynamic magnetization resonance enhancement of Co-based soft magnetic thin films induced by two-step oblique angle deposition

Abstract

Oblique angle deposition is an effective strategy to enhance the resonance frequency of magnetic thin films, but it often suffers from increased surface roughness, high damping, and reduced permeability, which limit their use in GHz integrated inductors. Here, we propose a two-step oblique angle deposition method to address this trade-off. At the optimal deposition angle of 30°, Co₉₀Nb₁₀ films exhibit an initial permeability of 404, a resonance frequency of 2.87 GHz, and a damping factor of 0.0062. These improvements are attributed to reduced roughness, suppressed dipolar interactions, and the promotion of nucleation-type domain reversal. When used as magnetic cores in thin-film inductors, the inductance is enhanced by 160% compared with air-core devices. This study demonstrates that the two-step deposition strategy effectively reconciles the conventional conflict between permeability and resonance frequency, offering a promising approach for GHz-range silicon-integrated inductors.