Direct observation of non-Gaussian distribution of local magnetic properties in ferromagnetic thin films

We report our experimental finding that magnetic properties of Co-based multilayer films are shown to exhibit their local variations far from the Gaussian ~or Lorentzian! distribution which are usually assumed. The local variations of the coercivity and the field dependence l(52]ln t/]H) were determined from measurements of the hysteresis loop and the field-dependent switching time t , respectively, on spatially resolved local regions 400 nm in size by means of a magneto-optical microscope magnetometer. We show that the two local magnetic properties inversely correlate with each other and a thermally activated process takes place during magnetization reversal on a submicrometer scale in ferromagnetic thin films.