Effect of Ag and Ti underlayer on the ordering in Fe/Pt multilayers

The Fe/Pt multilayers with Ag,Ti,Cu,Cr,Pt and Ta underlayers were prepared by DC magnetron sputtering on the heated glass substrates. After vacuum annealing at different temperatures, the FePt thin films with L1(0) ordering phase (L1(0)-FePt) were obtained. Results showed that the Ag and Ti underlayer prompt the ordering of FePt thin films, and the ordering temperature of FePt- L1(0) phase is reduced by at least 150 degrees C. It is also worth noting that the annealing time is shorter and the magnetic performance is excellent. The magnetic performance of samples with Ag underlayer is not sensitive to temperature at relative higher annealing temperature, whereas the coercivity of samples with Ti underlayer decreases obviously when the annealing temperature is higher than 500 degrees C. After annealing at 400 degrees C for 20 min, the in-plane coercivity of samples with Ag and Ti underlayer can be as high as 597kA/m, and 654kA/m, respectively, and the ratio of remanent magnetization to saturation magnetization reaches 0.81 and 0.94, respectively, implying the potential of the films as future magnetic recording media of ultrahigh density.