  Schemes of switching nanomagnetic memories via the effect of spin torque with
various polarizations of injected electrons are studied. Simulations based on
macrospin and micromagnetic theories are performed and compared. We demonstrate
that switching with perpendicularly polarized current by short pulses and free
precession requires smaller time and energy than spin torque switching with
collinear in plane spin polarization; it is also found to be superior to other
kinds of memories. We study the tolerances of switching to the magnitude of
current and pulse duration. An increased Gilbert damping is found to improve
tolerances of perpendicular switching without increasing the threshold current,
unlike in plane switching.

Mesoscale and Nanoscale Physics