Magnetic Recording Assisted by Spin-Transfer-Torque-Induced Magnetization Reversal and Dynamics

To advance hard disk drive areal densities, spin torque devices have been proposed for write gap (WG) inclusion, through magnetic layer reversal and/or large angle radio frequency (RF) oscillations. When spin torque-induced magnetization reversal assists the write field, the total moment to be flipped under the current density allowable for reliability must be considered. A layer with a low product of magnetization density and thickness (
$M_{s}t$
) can be easily flipped under low current densities
$ < 3\times 10$
⁸
A/cm
²
. A higher
$M_{s}t$
has better potential for areal density capability improvements, but >80% flipping only occurs at higher current densities. Furthermore, the amount of flipped magnetic moment is affected by the frequency of the alternating gap field. Real-time micromagnetic simulations of reversal under recording frequencies are presented. Multiple magnetic layers applied in the WG are also covered where the effects of reducing magnetic moment along the gap field and of generating RF field on the media may compete.