Magnetostatic interactions in antiferromagnetically coupled patterned media.
ABSTRACT In an array of closely spaced magnetic islands as in patterned media, magnetostatic interactions play a major role in widening the switching field distribution and reducing the thermal stability. Patterned antiferromagnetically coupled (AFC) media provide interesting systems for studying the effect of magnetostatic interactions on the reversal of closely spaced AFC bits in an array, as AFC structure helps to reduce the remanent magnetization (M(r)), leading to reduced magnetostatic interactions. Here, we study the magnetic reversal of single domain-patterned AFC CoCrPt:oxide bilayer system with perpendicular magnetic anisotropy, by imaging the remanence state of the bits after the application of a magnetic field with magnetic force microscopy (MFM). The influence of magnetostatic fields from the neighboring bits on the switching field distribution (SFD) for an entity in a patterned media is studied by varying the stabilizing layer thickness of the AFC structure and bit spacing. We observe a distinct increase in stability and coercivity with an increase in stabilizing layer thickness for the 40 nm spaced bits. This demonstrates the effectiveness of the AFC structure for reducing magnetostatic interactions in patterned media, such that high thermal stability can be achieved by the reduced M(r), without writability issues.
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ABSTRACT: The effect of magnetization of the spin-polarizing layer (SPL) on the magnetoresistance (MR) is investigated by using different compositions of CoxFe80-xB20 (x = 60, 40, and 20) as spin polarizers in Co/Pd multilayers-based pseudo-spin-valves with perpendicular magnetic anisotropy (PMA). In the case of as-deposited films, the giant magnetoresistance (GMR) was found to decrease with increase of CoFeB thickness from 5 angstrom to 10 angstrom. However, after post-annealing at 250 degrees C, 10 angstrom samples showed a peak of GMR in all compositions. Further increase in annealing temperature causes a reduction in GMR, which was found to be larger in samples with a lower saturation magnetization (M-s). As a function of SPL thickness, the GMR decreases in the case of as-deposited samples. However, post-annealed samples show a larger MR in case of thicker SPL. In the case of thick CoFeB SPL, the magnetization of the soft layer appears to be canted out of the plane. Among the three compositions investigated, the Co60Fe20B20 polarizer shows a stronger PMA due to its lower M-s, leading to the weaker demagnetization. (C) 2012 American Institute of Physics. [doi:10.1063/1.3676424]Journal of Applied Physics 01/2012; 111(7). · 2.21 Impact Factor
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ABSTRACT: During the past decade, magnetic recording density of HDD has doubled almost every 18 months. To keep increasing the recording density, there is a need to make the small bits thermally stable. The most recent method using perpendicular recording media (PMR) will lose its fuel in a few years time and alternatives are sought. Patterned media, where the bits are magnetically separated from each other, offer the possibility to solve many issues encountered by PMR technology. However, implementation of patterned media would involve developing processing methods which offer high resolution (small bits), regular patterns, and high density. All these need to be achieved without sacrificing a high throughput and low cost. In this article, we review some of the ideas that have been proposed in this subject. However, the focus of the paper is on nano-imprint lithography (NIL) as it fulfills most of the needs of HDD as compared to conventional lithography using electron beam, EUV or X-Rays. The latest development of NIL and related technologies and their future prospects for patterned media are also discussed.Recent patents on nanotechnology. 02/2007; 1(1):29-40.