Low-temperature ordering and enhanced coercivity of L10-FePt thin films with Al underlayer

FePt multilayer films with and without Al underlayer were prepared by magnetron sputtering on SiO2 substrate and subsequently annealed in vacuum. Experimental results suggest that the existence of Al underlayer can effectively reduce the ordering temperature and increase the coercivity of FePt films. Due to the slight larger lattice constant of Al underlayer than that of FePt films, [Fe (0.66 nm)/Pt (0.84 nm)]30 films begin to order at 350 °C and the coercivity of them reach to 5.7 kOe after annealing at 400 °C for half an hour.

Research highlights▶ Al underlayer is inserted between FePt films and SiO2 substrate. ▶ The annealing temperature and coercivity of FePt films can be lowed and enhanced respectively. ▶ No Al atoms are detected in the interior of FePt films. ▶ The mismatch between Al underlayer and FePt films causes the lower annealing temperature.