Perpendicular spin-torque switching with a synthetic antiferromagnetic reference layer

Spin-torque switching of perpendicular anisotropy nanopillar spin valve devices with synthetic antiferromagnetic reference layers is presented. The use of composite reference layer reduces the dipolar interaction with the free layer yielding two remanent states. We derive a complete current-field phase diagram including minor loops of the free layer where we determine the relative dipolar fields and effective spin polarization of the reference layer in both the parallel and antiparallel configurations. We find the magnetic response of the reference layer relatively insensitive to the spin polarized current which may prove advantageous for spin-torque applications.