Underlayer-enhanced perpendicular anisotropy of FePt films

Abstract

(0 0 1)-orientation FePt films were successfully fabricated on hydrogen-terminated Si(1 0 0) substrates by inserting Cu underlayers. By using the Co intermediate layer to suppress the diffusion of Cu and Si, the perpendicular coercivity reaches 6500 Oe after 300 °C postannealing. The dynamic-stress-induced ordering by the formation of Cu 3Si was the main reason for high coercivity. To improve the perpendicular anisotropy, Cu/CoFe/Ag composite underlayer was used. The large lattice constant of Ag provided a sufficient in-plane tensile static stress in FePt films. Both large perpendicular coercivity (8200 Oe) and good perpendicular squareness (∼0.9) were achieved for samples deposited at 300 °C.