Comparative evaluation of performance of percolated perpendicular media using FePt–MgO/Pt/Cr trilayer and FePt–MgO/MgO bilayer

• Published in: Journal of magnetism and magnetic materials Vol. 320; no. 22; pp. 3169 - 3173
• Main Authors: Sun, A.C., Tsai, Y.C., Hsu, Jen-Hwa, Kuo, P.C., Huang, H.L.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 01-11-2008; Elsevier
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; FePt; Interfacial magnetic properties (multilayers, magnetic quantum wells, superlattices, magnetic heterostructures); Magnetic properties and materials; Magnetic properties of surface, thin films and multilayers; Magnetic recording materials; Percolated perpendicular media; Perpendicular magnetic recording; Physics; Studies of specific magnetic materials; Underlayer; FePt; Underlayer; Perpendicular magnetic recording; 75.50.Ss; 75.50.Bb; 75.50.Vv; 75.60.−d; Percolated perpendicular media; 74.25.Ha; Grain boundaries; Iron alloys; Close packing; Multilayers; Platinum; Coercive force; Percolation; Recording material; High resolution electron microscopy; 75.60.-d; Magnetization; Magnesium oxide; Platinum alloys; Comparative evaluations; Precipitates; Transmission electron microscopy; Transition elements; Chromium; Microstructure
• ISSN: 0304-8853
• DOI: 10.1016/j.jmmm.2008.08.033

(Fe
48Pt
52)
100−
x
–(MgO)
x
films were used to examine the performance of a perpendicular percolated medium. Two underlayers, Pt(0
0
1)/Cr(0
0
2) and MgO(0
0
2), were used for comparison. The (Fe
48Pt
52)
100−
x
–(MgO)
x
film with the MgO underlayer exhibits a strong preference to segregate at FePt grain boundaries. The microstructure with small closely packed MgO particles (2–4
nm) dispersed uniformly in the L1
0 FePt matrix was achieved in the Pt/Cr underlayered sample. Structural data reveal that the precipitate is crystallographically coherent with the surrounding L1
0 FePt phase and preserves good lattice alignment. Magnetic results indicate significant pinning behavior for those introduced non-magnetic columns with an enhanced coercivity of about 70%—much greater than that of the MgO underlayered samples. Percolated perpendicular medium can be realized in the FePt system and a Pt(0
0
1)/Cr(0
0
2) underlayer promotes the formation of pinning sites within the FePt grains.