Reversal modes, thermal stability, and exchange length in perpendicular recording media
D. Suess, T. Schrefl and J. Fidler,
IEEE Trans Magn., 37 (2001) 1664-1666.
Micromagnetic simulations are performed to investigate the reversal process
and the thermal stability of a grain of a typical perpendicular recording
media (Co Cr). The integration of the LLG equation yields that the reversal
process changes slowly and steadily from coherent rotation to nucleation with
increasing column length. The region between homogeneous rotation and
nucleation becomes smaller and is shifted to smaller column lengths if the
damping constant is reduced from alpha= 1 to alpha=0.02 . In the weakly damped case
very fast switching modes exist if the switching field is only slightly
larger than the coercive field. In this small regime the switching time
increases with higher switching fields. Using solutions of LLG simulations,
energy barriers between the two stable states at zero field are estimated.
For column lengths larger than 30 nm the energy barrier for inhomogeneous
reversal processes are smaller than for coherent rotation.
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Feb. 13, 2001