Experimental evidence of a1∕Hactivation law in nanostructures with perpendicular magnetic anisotropy

Abstract

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.