Subnanosecond magnetization reversal in magnetic nanopillars by spin angular momentum transfer

Abstract

Sub-ns magnetization switching has been triggered by spin momentum transfer in pulsed current in pillar shaped CoFe∕Cu∕CoFe trilayers. By analyzing the change in magneto-resistance induced after the application of individual short current pulses (100ps–10ns), we measured the probability of magnetization reversal as a function of the current pulse magnitude, polarity and duration, at various temperatures between 150 and 300K. At all studied temperatures, the reversal process can take place within a few 100ps. The energy cost of the reversal scales favorably with the switching speed and decreases in the 1pJ range when using 100ps current pulses at 300K. Significantly higher switching speeds are obtained at lower temperatures, which is opposite to a thermal activation of the reversal.

Coherent control of nanomagnet dynamics via ultrafast spin torque pulses

“…In contrast with previous measurements where the spin torque is applied throughout a large fraction of a precession cycle, [14][15][16][17][18] in our experiments the magnetization evolves freely except for short time intervals when it is driven by the spin torque. By using ultrashort spin torque "impulses," we can access a previously unexplored regime in which nanomagnet dynamics is strongly affected by the timing of the spin torque pulses with respect to the underlying free precession orbits.…”

Distribution of the magnetization reversal duration in subnanosecond spin-transfer switching

“…STT can also simply switch the magnetization of a uniaxial nanomagnet [7], which is considered as a promising route for memory applications [8], since this type of switching has proven deep sub-ns potential [9,10]. However, previous investigations have concluded that the reversal speed in the sub-ns regime has insufficient reproducibility.…”

Ultrafast switching of a nanomagnet by a combined out-of-plane and in-plane polarized spin current pulse

“…Fast pulsed-current reversal experiments have previously been performed 3,4,5,6,7,8 on current-perpendicular-to-the-plane (CPP) spin valve devices in which both the polarizing fixed magnetic layer and the switchable free magnetic layer have moments that lie in the sample plane in equilibrium (see Fig. 1b inset).…”