L10 Fe-Pd Synthetic Antiferromagnet through an fcc Ru Spacer Utilized for Perpendicular Magnetic Tunnel Junctions

Magnetic materials that possess large bulk perpendicular magnetic anisotropy (PMA) are essential for the development of magnetic tunnel junctions (MTJs) used in future spintronic memory and logic devices. The addition of an antiferromagnetic layer to these MTJs was recently predicted to facilitate ultrafast magnetization switching. Here, we report a demonstration of a bulk perpendicular synthetic antiferromagnetic (PSAFM) structure comprised of a (001) textured Fe-Pd/Ru/Fe-Pd trilayer with a face-centered-cubic (fcc) phase Ru spacer. The L10 Fe-Pd PSAFM structure shows a large bulk PMA (Ku∼10.2 Merg/cm3) and strong antiferromagnetic coupling (-JIEC∼2.60 erg/cm2). Full perpendicular magnetic tunnel junctions (PMTJs) with a L10 Fe-Pd PSAFM layer are then fabricated. Tunneling magnetoresistance ratios of up to approximately 25% (approximately 60%) are observed at room temperature (5 K) after postannealing at 350 °C. Exhibiting high thermal stabilities and large Ku, the bulk PMTJs with an L10 Fe-Pd PSAFM layer could pave a way for next-generation ultrahigh-density and ultralow-energy spintronic applications.