Experimental evidence of a 1/H activation law in nanostructures with perpendicular magnetic anisotropy -: art. no. 100402

The dynamical reversal of the magnetization in perpendicular magnetized nanostructures with typical lateral sizes of about 100 nm has been studied by magneto-optical Kerr effect on time scales extending from the quasistatic regime down to 20 ns. By modeling the reversal dynamics using a thermally activated nucleation process, it has been shown that the barrier height depends on the inverse of the applied field. A clear saturation of the dynamical coercive force at a value close to the anisotropy field was observed in the nanosecond range. This study allows a new interpretation of magnetization reversal in perpendicular systems and leads to criteria of stability in magnetic recording media.