MAGNETIC VISCOSITY AND SWITCHING VOLUMES OF ANNEALED FE PT MULTILAYERS/

Magnetic viscosity and the phenomenon of the sweep-rate dependence of the coercivity are important for the characterization of magnetic reco rding media. The activation volume of magnetization reversal. or switc hing volume is directly related to medium noise. The magnetic viscosit y behavior of annealed Fe/Pt multilayers was studied and the switching volumes were obtained by both measurements of the sweep-rate dependen ce of coercivity and time dependence of magnetization. It is found tha t samples with larger coercivities have smaller switching volumes, and an estimate of the magnetic grain diameter is about 9 nm. The coerciv ity mechanisms are also discussed. (C) 1996 American Institute of Phys ics.