Structural and Magnetic Properties of FePt and FePt-Al2O3 Thin Films

Abstract

The magnetic and structural properties of FePt and FePt-Al2O3 films deposited by rf-sputtering on 7059 corning glass substrates were investigated. The coercivities of the films can be adjusted from 20 to 12.3 kOe through controlling the ordering degree of the FePt phase. With the increasing annealing temperature TA from 100 to 650 degreesC, the average grain size of FePt grains increased from about 10 to 50 nm in the FePt films, while it kept almost a constant of about 10 nm in the alumina-added films. The measurements of the deviation Deltam*(H) as a measure for particle-particle interaction and SFD (switching field distribution) revealed that the addition of alumina contributed to diluting the intergranular exchange coupling interaction. In the case of the FePt-Al2O3 (25 vol%) films with varying film thickness from 20 to 180 nm annealed at 550 degreesC for one hour, no obvious changes in structural and magnetic properties due to the variation of film thickness was detected. Grain size was in the vicinity of 10 nm, squareness S about 0.9, coercivity squareness S-* almost a constant of about 0.85, and the in-plane coercivities kept high value of about 5.5 kOe.