Spin-Transfer Switching and Thermal Stability in an FePt/Au/FePt Nanopillar Prepared by Alternate Monatomic Layer Deposition

We fabricated a current-perpendicular-to-plane giant magnetoresistance (CPP-GMR) nanopillar with a 1-nm-thick FePt free layer having perpendicular anisotropy using the alternate monatomic layer deposition method. Nanopillars consisting of [Fe (1 monolayer (ML))/Pt (1 ML)] n ( n : the number of the alternation period) ferromagnetic layers and an Au spacer layer showed spin-transfer induced switching at room temperature. An average critical switching current density ( J c0 ) of 1.1 × 10 7 A/cm 2 with a large thermal stability parameter (Δ) of 60 was obtained in a nanopillar with a free-layer thickness of 1.02 nm ( n =3) and a pillar diameter of 110 nm. The ultrathin free-layer with high perpendicular anisotropy is effective to obtain both large Δ and small J c .