Microstructural segregation in CoCrTa and CoCrPt longitudinal magnetic recording media

Inaba, Nobuyuki; Yamamoto, T.; Hosoe, Y.; Futamoto, Masaaki

doi:10.1016/s0304-8853(96)00681-6

Cited by 66 publications

(22 citation statements)

References 13 publications

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“…Due to Cr segregation, there is a microscopic distribution of M s in both kinds of films. 8,9 This distribution is likely to cause the reduction of magnetic cluster size of CoTb layer through the distribution of interfacial exchange coupling between the granular and CoTb layers.…”

Section: Resultsmentioning

confidence: 99%

Recording performance and magnetization switching of CoTb/CoCrPt composite perpendicular media

Uwazumi

Shimatsu

Sakai

et al. 2002

Journal of Applied Physics

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Magnetic properties, recording performance, and thermal stability of CoTb amorphous/CoCrPt granular composite media are discussed. Thermal stability at low recording density of the composite media with CoCrPtB improves significantly as CoTb thickness increases, in accord with the increase of loop squareness, Mr/Ms. The media having CoTb thickness of more than 6 nm show almost no signal decay. Moreover, the signal-to-medium-noise ratio, SNR, improves with increasing CoTb thickness up to 6 nm. CoTb(6 nm)/CoCrPtB(20 nm) medium shows the best SNR performance under the present experimental conditions with no thermal decay. Media noise of the composite media with CoCrPt increases super linearly from ∼300 kfci, which is caused by the percolation of the recorded bits, probably due to the strong exchange coupling in the CoTb layer. The media with CoCrPtB shows less media noise than that with CoCrPt, and the super-linear increase of this media noise starts at ∼400 kfci which is higher than that of the media with CoCrPt. It is thought that the well-segregated grain structure of CoCrPtB layer, having the enhanced and fine distribution of Ms, reduces the magnetic cluster size effectively, resulting in the reduction of the media noise.

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Section: Resultsmentioning

confidence: 99%

Recording performance and magnetization switching of CoTb/CoCrPt composite perpendicular media

Uwazumi

Shimatsu

Sakai

et al. 2002

Journal of Applied Physics

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“…The ferromagnetic energy per unit area, , is (1) where , , and . The total exchange and anisotropy energies, and , are functions of the homogeneous values and , modified within the material segregation region by the small parameters and , and the localized Gaussian distrubution .…”

Section: The Solutionmentioning

confidence: 99%

“…In order to properly construct low noise films from cobalt-chromium type alloys (i.e., CoCrTa), we must be able to model the effect of the abrupt change in anisotropy axis from grain to grain, as well as the effects of material segregation between grains. Material segregation (i.e., chromium) at the interface of the grains has been experimentally observed [1], [2], and shown to follow a Gaussian distribution [3], [4]. The changes in anisotropy and exchange energies of the media have a significant effect on the magnetic rotation across the grain boundary.…”

Section: Introductionmentioning

confidence: 99%

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Analytic solution for magnetic orientation between grains

2001

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Transmission electron microscopy experiments have shown that CoCrTa films for hard disk drives experience chromium segregation at grain boundaries. The resultant changes in the ferromagnetic parameters of the material together with the variation in the anisotropy direction from grain to grain are determining factors governing its magnetic behavior. In this paper, the case of two grains, differing in the direction of their magnetic anisotropy and possessing a change in their material content at the interface which we model by a Gaussian distribution, is solved analytically. Effects due to the diffuse interface such as localized regional changes in the anisotropy, exchange energy, and magnetic moment are included using perturbation theory. One of the outputs is the profile of the magnetization orientation in the inhomogeneous medium-thus yielding the smoothness and extent of the change. Such knowledge, in addition to its intrinsic scientific interest, points the direction, both for large scale computer calculations and for media improvement.

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“…So far, most of the studies on CoCrPt alloy films concentrated on the control of the grain size and the grain size distribution, which is essential to media processing and to suppress the media noise by reducing the intergranular exchange interaction between the neighboring grains [7][8][9]. Studies of magnetization reversal of CoCrPt alloy films published so far have been performed by macroscopic measurement techniques as well as by theoretical magnetization reversal models [10,11].…”

Section: Introductionmentioning

confidence: 99%

Magnetization reversal behavior of nanogranular CoCrPt alloy thin films studied with magnetic transmission X-ray microscopy

Fischer

Eimüller

et al. 2005

Journal of Magnetism and Magnetic Materials

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Microstructural segregation in CoCrTa and CoCrPt longitudinal magnetic recording media

Cited by 66 publications

References 13 publications

Recording performance and magnetization switching of CoTb/CoCrPt composite perpendicular media

Recording performance and magnetization switching of CoTb/CoCrPt composite perpendicular media

Analytic solution for magnetic orientation between grains

Magnetization reversal behavior of nanogranular CoCrPt alloy thin films studied with magnetic transmission X-ray microscopy

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