Characteristics of AP bias in spin valve memory elements

Spin valve memory element biased with a pair of antiparallel (AP) coupled ferromagnetic layer was analyzed and modeled via micromagnetic simulation. In an AP structure, an external field results in a torque, causing the antiparallel magnetization (AP) axis to rotate towards the direction orthogonal to the field. In addition, due to its strength difference between the two AP layers, the magnetostatic field from the free layer of the spin valve can lead to irreversible AP axis flipping. This irreversible flipping can be effectively prevented by applying an AF/F exchange pinning to one of the AP layers to overcome the differential field from the free layer.