Magnetization reversal dynamics in mesoscopic Ni₈₀Fe₂₀ dots

The magnetization reversal dynamics in permalloy dots (20 ∼ 400 μm diameter) has been investigated as a function of the applied field amplitude H₀ and frequency Ω using scanning Kerr microscopy. An increase in the dynamic coercivity with reduced size is observed for d < 100 μm in the frequency range up to 800 Hz. The loop area A follows the scaling relation A ∝ H^α₀Ω^β, with α ≈ 0.14 and β ≈ 0.50 throughout the entire size range studied. These results demonstrate that the dynamic scaling behavior is universal even though the lateral size influences the domain structure and magnetic reversal behavior.