Fabrication of nonepitaxially grown double-layered FePt:C/FeCoNi thin films for perpendicular recording

Abstract

A noneptaxially grown double-layered thin-film medium of nanocompsite FePt:C with a FeCoNi soft underlayer for high-density perpendicular magnetic recording was fabricated and investigated. Square-shaped perpendicular loops with a remanance ratio nearly equal to one and a coercivity as large as 8.5 kOe were obtained for this ordered FePt:C double-layered medium. The formation of the ordered L10 phase is confirmed by electron diffraction experiments. Transmission electron microscope observations reveal that FePt grains with a uniform size less than 5 nm are embedded in the C matrix and appear to be well isolated. Our results show that nonepitaxially grown (001) textured double-layered nanocomposite L10 FePt-based films with perpendicular anisotropy are a promising candidate to realize extremely high-density perpendicular recording.

Assembly of high-anisotropy L10 FePt nanocomposite films

“…Recently, non-epitaxially grown, highly (0 0 1)-textured L1 0 FePt [9,10] and FePt based fi lms [18] have been obtained by using multilayer deposition plus post annealing. It is found that orientations of FePt grains are affected by many preparation parameters, such as initial as-deposited fi lm structure, composition, annealing time and so on [19,20]. Fig.…”

“…The loop shows perpendicular anisotropy with square shape in the perpendicular direction due to the preferential FePt L1 0 (0 0 1) texture. The perpendicular loop shows large coercivity (H c = 6.2kOe) and high remanence ratio (S=0.9) [20].…”

“…The large uniaxial anisotropy K 1 of FePt is the basis for creating coercivity H c in L1 0 -based permanent magnets and magnetic recording media [14,20]. However, the corresponding Stoner-Wohlfarth prediction H c =2K 1 /μ o M s signifi cantly overestimates the co- ercivity, because it ignores the real structure of the magnets [25,26].…”

Nanomagnetic Structures: Fabrication and Interactions

“…The requirement of narrow size distribution can be met by creating particles with a gas aggregation cluster deposition system [1]. Crystallographic texturing of clusters could be of great use in perpendicular magnetic recording and can readily be done by multi-layer sputter deposition and annealing [2]. Depending on the choice of matrix, the final goal of decoupled grains is achieved.…”

Highly (001)-oriented Ni-doped L1 FePt films and their magnetic properties

“…The multilayering of Fe/ Pt and dimensions of the Fe and Pt individual layers, annealing temperature and time, total film thickness, alloy composition, etc., appear to play an important role in obtaining the films with c axis perpendicular to the film plane. 3,4 Recent modeling results suggested that the media for future 1 Tbit/ in. 2 should have small grain size ͑d ϳ 4 nm͒ and narrow distribution ͑ / d ϳ 0.07͒, moderate anisotropy ͑H k ϳ 25 kOe͒, coercivity ͑H c ϳ 5-8 kOe͒, and saturation magnetization ͑M s ϳ 750 emu/ cc͒.…”