Magnetization Switching Dynamics of Electrodeposited Fe–Ni Thin Films

Magnetic thin films with fast magnetization switching and low Gilbert damping are crucial for devices working at high frequency with low power consumption. In this work, composition-controlled high-quality Fe–Ni alloy thin films were electrodeposited on ITO/glass substrates and their magnetization switching behavior was investigated using MOKE and FMR. The phase of deposited alloy transformed from FCC to mixed BCC and FCC for high Fe content films. All the deposited alloy films display granular morphology and possess soft magnetic characteristics with low coercivity (H_c < 50 Oe). Magneto-optic Kerr effect hysteresis along with simultaneous domain imaging reveals that the alloy composition influences anisotropy, domain structure, and magnetization switching process. The alloyed films exhibited fourfold surface anisotropy. The magnetization reversal in pure Fe and Ni samples occurs through stripe-like domains, whereas band and ripple-like domains were evident for the alloyed films. Fast magnetization switching within a minimum field range of ~ 3 Oe was observed for Fe₂₅Ni₇₅ sample. The ferromagnetic resonance measurements revealed that the Fe₂₅Ni₇₅ alloy films exhibit lowest Gilbert damping (α = 0.024) compared to pure Fe and Ni films. In summary, these findings offer valuable insight for tailoring the magnetic properties of Fe–Ni alloy thin films with appropriate alloy composition.