Improved perpendicular magnetic anisotropy of Pr-Fe-B films with Ta underlayer

Perpendicular magnetic anisotropy (PMA) of sputter-prepared Pr-Fe-B films on the glass substrates were improved by inserting a Ta underlayer. Pr-Fe-B directly sputtered on glass substrate exhibits soft in-plane magnetic property due to the amorphous phase or poor crystallization. When Ta layer is introduced as an underlayer, strong PMA with attractive hard magnetic properties are obtained. Their magnetic properties highly depend on the thickness of Ta underlayer (t). Large out-of-plane coercivity (Hc⊥ > 800 kA/m) is attained for t in the range of 10-75 nm, where the Pr-Fe-B film sputtered on 50-nm-thick Ta underlayer shows stronger PMA due to promotion of the formation for the Pr2Fe14B phase with Ta underlayer. Therefore, it was demonstrated that inserting a Ta underlayer with suitable t (∼50 nm) between magnetic layer and glass substrate promotes to obtain Pr-Fe-B film with excellent PMA.