Microstructure and magnetic properties of Fe100−xPtx alloy films

Abstract

Polycrystalline Fe 100Ϫx Pt x alloy thin films with Pt composition xϭ25-67 at. % were prepared by dc magnetron sputtering on natural-oxidized silicon wafer substrates, then postannealed in vacuum at various temperatures and over different periods. The effects of film composition, magnetic layer thickness, annealing temperature, and annealing time on the magnetic properties parallel and normal to the film plane were investigated. Films with high in-plane coercivity could be obtained by annealing the films in the temperature range between 400 and 650°C. Optimum in-plane squareness and coercivity of the film occurred at a film composition of Fe 50 Pt 50 with thickness of about 200 nm after annealing at 600°C for 30 min. The analyses of transmission electron microscopy diffraction patterns indicated that this annealed Fe 50 Pt 50 film was nearly entirely in the fct ␥ 1 -FePt phase. The average grain size of this Fe 50 Pt 50 film was about 85 nm. The grain size was almost independent of the cooling rate after annealing, but the magnetic hardening mechanism and coercivity of the annealed film was largely dependent on the cooling rate.

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

“…In-plane coercivities that are in the vicinity of 5.5 kOe are always higher than those perpendicular. Kuo et al [19] investigated the influence of film thickness on the magnetic properties of the post-annealed Fe 50 Pt 50 films. They found that, with the decreasing film thickness d coercivities showed abrupt reductions when d was less than 200 nm, and that coercivities were about 1 kOe when d was lower than 60 nm.…”

Composition and film thickness effects on microstructure and magnetic properties of ordered L10-structured Fe100−xPtx films

“…The FePt films fabricated by the magnetron sputtering without substrate heating generally have a disordered face-centered-cubic (fcc) structure. High-temperature annealing above 500 • C is necessary for the FePt films to transform from the disordered fcc structure into the ordered fct structure [2,3], and above 650 • C for the FePt based nanocomposite films [4][5][6][7][8]. The third element doped into the FePt films makes the transformation temperature decrease because of the increase of the diffusivities of Fe and Pt atoms [9,10].…”

Dependence of magnetic properties on the film thickness and Pt atomic fraction of post-annealed Fe1−xPtx-C granular films on MgO(100) and SiO2/Si(100) substrates

“…Mi). ordered fct structure [8][9][10][11]. Recently, the nonmagnetic matrixes including C, SiO 2 , TiO 2 , Ta 2 O 5 and SiN x have been used to isolate the FePt grains for decreasing the signal-to-noise ratio [12][13][14][15][16].…”