Effect of a Boron Underlayer on the Ordering and Orientation of Sputtered FePt Film

FePt multilayer films with a boron underlayer are prepared on Si (100) substrates using magnetron sputtering and vacuum annealing is carried out to obtain the hard magnetic L1₀ phase. According to the microstructural and magnetic measurement results, the ordering of the FePt films is facilitated at low annealing temperatures while it is blocked at high ones by introducing boron. Moreover, (001) orientation of the samples is obviously improved by inserting a boron underlayer, which is further confirmed by the MFM analysis. The relevant mechanism is discussed by considering the diffusion of boron atoms and the consequential in-plane tensile stress.