Sub-nanosecond non-Arrhenius magnetic switching in perpendicular multilayers

Measurements are presented of sub-nanosecond magnetization reversal processes of perpendicularly magnetized (CoCr/Pt) multilayers using real-time Kerr microscopy. The multilayers are placed on a ring-type recording head which is used as a sub-ns risetime field source. In the gap of the write head the magnetic field direction changes rapidly from in-plane to out-of-plane. By scanning the laser beam across the gap the influence of the field angle on the reversal process is studied. The reversal time depends critically on the field angle, and faster switching occurs close to the gap (pole edge) due to the increase of the in-plane field. On the time scale of the study, the rotational (non-Arrhenius) switching seems to dominate.