Switching characteristics of magnetic tunnel junctions with a synthetic antiferromagnetic free layer

The array of synthetic antiferromagnetic magnetic tunnel junctions (MTJs) consisting of the TiN/PtMn (15 nm)/CoFe (1.5 nm)/Ru (0.8 nm)/CoFe (1.5 nm)/AlO (1.2 nm)/NiFe (t₁ nm)/Ru (0.8 nm)/NiFe (t₂ nm)/Ta (10 nm)/TiN structure was fabricated into submicrometer dimensions. Magnetization switching field and magnetic domain structure were investigated by micromagnetic modeling as well as remanent magnetoresistive measurement. Domain structure was investigated to understand switching characteristics. The switching field depends on the thicknesses difference of two magnetic layers consisting of SAF free layer structure. When the thickness difference became 1.5 nm, the switching field was reduced to around 20 Oe with improved squareness.