Subnanosecond magnetization reversal in magnetic nanopillars by spin angular momentum transfer

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 (100 ps-10 ns), we measured the probability of magnetization reversal as a function of the current pulse magnitude, polarity and duration, at various temperatures between 150 and 300 K. At all studied temperatures, the reversal process can take place within a few 100 ps. The energy cost of the reversal scales favorably with the switching speed and decreases in the 1 pJ range when using 100 ps current pulses at 300 K. Significantly higher switching speeds are obtained at lower temperatures, which is opposite to a thermal activation of the reversal. (C) 2004 American Institute of Physics.