Enhanced perpendicular coercivity of ultrathin perpendicularly magnetized Tb–Fe–Co films on silicon substrates using a thin Pt underlayer

We have studied the effect of an additional thin Pt underlayer on the magnetic properties of ultrathin perpendicularly magnetized TbFeCo films grown on silicon substrates. We have demonstrated that the presence of a thin Pt underlayer can enhance the perpendicular coercivity of ultrathin TbFeCo films with thickness down to 1 nm while preserving their low saturation magnetization. This can be attributed to the hybridization of Pt and Co orbitals, which induces the strong interfacial perpendicular anisotropy of Co/Pt and/or CoFe/Pt. These characteristics are potentially useful to reduce the critical current density induced magnetization switching and enhance the thermal stability of a magnetic tunnel junction and the current-induced domain wall motion in a nanowire made out of the ultrathin TbFeCo magnetic layer.