Diffusion process and formation of super-spin-glass state in soft magnetic Fe/Pt system.

We report results on surface and micromagnetic structures of Fe thin films consisting of a Pt underlayer. We use atomic force microscopy to study the surface structure evolution of the Fe films as a function of annealing time at an annealing temperature of 800 °C. Power spectral density analysis shows saturation in roughness exponent after 15 min of annealing. However, lateral correlation length and roughness continue to increase for up to 45 min. At high annealing temperature, the authors find two separate phase correlation lengths and a single surface correlation length indicating super-spin-glass state in the system.