Effects of stacking faults on magnetic viscosity in thin film magnetic recording media

Dova, P.; Laidler, H.; O’Grady, K.; Toney, Michael F.; Doerner, M.

doi:10.1063/1.369593

Cited by 46 publications

(28 citation statements)

References 27 publications

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“…This apparent discrepancy is, again, likely due to different media compositions, growth conditions, seed/underlayers, as well as different Pt concentration regimes. It is indeed surprising that we do not observe any change in stacking fault density while the amount of the fee phase increases, since the formation of stacking faults is one mechanism for transforming hcp into fee [26,311. This may be a result of the fast sputter deposition of these alloys kinetically limiting equilibrium.…”

Section: Discussionmentioning

confidence: 85%

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High Anisotropy CoPtCrB Magnetic Recording Media

Toney¹

2003

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We describe the synthesis, magnetism and structure of CoPtCrB alloys with Pt concentrations from 10 -43 %. The Cr concentration in the alloys was 15-17 % and the B concentration was 9-11 %. The magnetic anisotropy and coercivity increase with increasing Pt up to M 30%, plateau at M 35,000 Oe and w 6000 Oe, respectively, and then decrease. Transmission electron microscopy results show the media form fine, isolated grains for all Pt concentrations. X-ray diffraction measurements show that with increasing Pt an fee Co-alloy phase is progressively formed at the expense of the hcp Co-alloy and that this fraction becomes significant for > 35% Pt. The formation of the fee phase likely causes the behavior in the anisotropy. No Pt concentration dependence is observed for the stacking fault density. The X-ray data show that with increasing Pt the CoPtCrB alloy lattice parameters exhibit two distinct regions with the slope changing at 16 % Pt. The presence of these two regions is discussed.

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Section: Discussionmentioning

confidence: 85%

“…4 and the line is a guide to the eye. Parts (a), (b) and (c) are the total fee fraction, the growth fault probability, and the deformation fault probability [26], respectively. …”

Section: Discussionmentioning

confidence: 99%

High Anisotropy CoPtCrB Magnetic Recording Media

Toney¹

2003

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“…It is known that the grains containing SFs and fcc phases along the c axis of a hcp crystal structure will cause a K u reduction due to the magnetic soft nature of these defects. [1][2][3][4][5][6] This explains the trend that the K u of continuous Co 1−x Pt x alloy films peaks at ϳ30 at. % of Pt and decreases quickly with further increase in Pt at.…”

Section: Introductionmentioning

confidence: 72%

Effects of substrate bias on magnetocrystalline anisotropy Ku of CoPt thin films with increasing Pt content

Yuan

Laughlin

2009

Journal of Applied Physics

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The magnetocrystalline anisotropy (Ku) of continuous Co1−xPtx alloy films peaks at ∼30 at. % of Pt. Further increase in Pt at. % decreases Ku quickly probably due to the increasing density of stacking faults (SFs) and the fcc phases. The effect of substrate bias has been studied in various compositions of CoPt films. Ku increases from 8×106 to 1.1×107 ergs/cm3 when −50 V bias was applied to Co60Pt40 films and decreases with further increase in bias. Pt at. % slightly increases from 40 to 43 at. %, which is opposed to the initial Ku increase. However, the SF density and the fcc content are greatly reduced in the biased samples. The transmission electron microscopy images of the biased films show less faulted atomic planes in the hcp CoPt grains. Such improvement in structural defects helps increase Ku in magnetic thin films.

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“…The magnetic properties of thin films are very sensitive to microstructures such as stacking faults or local fcc-like regions. [1,2] It was found that the existence of the stacking faults in media causes serious bit instability and reading noise, and, thus, it is becoming an interesting topic in both academic interests and in a practical sense, to avoid the stacking faults in this case. According to the study on the martensitic transformation of Co and Co-based bulk alloys, the stacking faults are responsible for this phase transformation; therefore, a comprehensive description of stacking faults as well as the phase transformation of Co is crucial for a better understanding of the microstructures of Co-based thin films.…”

Section: Introductionmentioning

confidence: 98%

Molecular-dynamic simulations of martensitic transformation of cobalt

Jiang

Oikawa

Ikeshoji³

2005

Metall Mater Trans A

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With a potential-energy function of Co described by the embedded-atom method (EAM), moleculardynamics (MD) simulations were performed for a series of initial fcc configurations with different types of dislocations or preset hcp embryos. The gliding process of a Shockley dislocation on a closepacked plane has been observed, which starts from the origin of the dislocation and proceeds at a high speed of 280 m/s toward a certain direction. An atom which has been swept by the dislocation line was detected to contribute a displacement close to the Burgers vector of a Shockley dislocation. It is in this way that a new stacking sequence is produced and an hcp lamella grows in the fcc structure. A similar gliding process has been observed in the case where an intrinsic stacking fault is preexisting in the fcc structure. The transformation is, again, toward forming a local hcp region. These results prove that a special dislocation in the fcc structure can act as an embryo of the hcp, as described in many dislocation mechanisms of the martensitic transformation. The phase-transformation process of Co has been further reproduced by a simulation initiated from an fcc/hcp two-phase configuration. It yields a single hcp crystal as the final transformed product.fcc → hcp

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Effects of stacking faults on magnetic viscosity in thin film magnetic recording media

Cited by 46 publications

References 27 publications

High Anisotropy CoPtCrB Magnetic Recording Media

High Anisotropy CoPtCrB Magnetic Recording Media

Effects of substrate bias on magnetocrystalline anisotropy Ku of CoPt thin films with increasing Pt content

Molecular-dynamic simulations of martensitic transformation of cobalt

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