Magnetic reversal in perpendicularly oriented thin films subjected to picosecond magnetic fields (abstract)

The magnetic reversal mechanism in perpendicularly oriented, premagnetized Co based thin film alloys, induced by ultra short magnetic field exposure of a few picoseconds duration has been studied. Field pulses with a magnitude of several thousand Tesla were generated by the 50 GeV final focus electron beam at the Stanford Linear Accelerator Center (SLAC). Characteristic remanent domain patterns are observed in these films long after field exposure using polar Kerr microscopy. Complete reversal of the magnetization is found to occur during a single spin precession event of 6.0 ps duration where the inplane‐field amplitude is greater or equal to the macroscopically determined perpendicular anisotropy field. Further, a wide transition range, dividing the reversed and nonreversed regions is observed which is broken into a quasi periodic stripe domain structure with stripe‐width 0.3 μm. As a main result of this experimental study we find that magnetization reversal on this time scale is solely governed by the intrinsic effective field, i.e., anisotropy‐ and demagnetization‐field contributions, rather then by complex curling and buckling mechanisms. Unique insight into fundamental spin reversal mechanisms and their ultimate speed in thin magnetic recording films is provided by these experiments.