Fractal domain structures in thin amorphous films

The remagnetization processes in thin films of rare earth - transition metal amorphous alloys were theoretically and experimentally investigated. Domain wall motion are known to play a key role in the decay of the metastable state via nucleation. Considering Bloch domain wall we can reduce magnetostatic equations to Laplace equation for magnetostatic potential φ Δφ = 0 The domain wall motion in an external magnetic field which slightly exceeds the coercive force is determined mainly by the fluctuations of magnetic parameters and cannot be treated as continuous one. The jump probability between neighbouring stable states of domain wall is characterized by the difference of the local free energy of stable and metastable phases P ˜ exp (-ΔF/T) Monte Carlo simulation based on the (1) and (2) yields us that the domain structures can be interpreted as Laplace fractal with fractal dimension d f , determined by the factor z = M 2 s /T, where M s is saturation magnetization, and T is the temperature.