High power spin-transfer induced magnetization precession in synthetic antiferromagnetic layers pinned by exchange bias

This paper studied spin-transfer induced magnetization dynamics in samples with a synthetic pinned layer and very soft free layer, patterned into square pillars with a lateral size of the order of 100 nm. The free and the reference layers have been laminated by insertion of very thin Cu layers, so as to increase the resistance of the active part of the spin-valves. The resistance of the pillars was of the order of 5Omega, and the measured magnetoresistance reached 2.5%. The coercivity of the free layer varied between 5 and 150 Oe and a magnetostatic coupling of the same order of magnitude was measured in most cases, favoring the antiparallel state. The exchange bias field of the synthetic layer was commonly around 1200 Oe. The critical current densities for switching the free layer were of the order of 107 A/cm
²
.