Compositional Microstructure and Micromagnetics of Co-Based Thin Film Media

Futamoto, Masaaki; Inaba, Nobuyuki; Hirayama, Yoshiyuki; Ito, K.; Honda, Yukio

doi:10.1557/proc-517-243

Cited by 16 publications

(4 citation statements)

References 22 publications

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“…One possible cause of this rather large inhomogeneous strain is the distribution of Cr concentration within a grain due to the Cr segregation to grain boundaries. 30 The particle dimensions obtained using this procedure are shown in Table II. They are the same for both C1 and C2, but are markedly anisotropic.…”

Section: Structural Resultsmentioning

confidence: 99%

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

Dova

Laidler

O’Grady

et al. 1999

Journal of Applied Physics

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There is much interest in crystallographic defects in thin film magnetic recording media and their role in influencing recording performance such as media noise and thermal loss. In this article we report a correlation between the magnetic viscosity in CoPtCr thin film media, which is the origin of thermal loss effects, and the concentration of local fcc-like regions. The concentration of these defects ͑the type and density of stacking faults͒ was varied by growth on different underlayers ͑Cr and CrTa/Cr͒ and was measured with grazing incidence x-ray scattering using synchrotron radiation. We show that a substantial percentage of local fcc regions in an otherwise hcp cobalt alloy film leads to significant magnetic viscosity effects at quite modest magnetic fields. We find that the activation volume is reduced for a sample with a higher percentage of fcc-like regions and suggest that this can be understood in terms of the effect of weak links acting to stabilize local micromagnetic configurations.

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Section: Structural Resultsmentioning

confidence: 99%

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

Dova

Laidler

O’Grady

et al. 1999

Journal of Applied Physics

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“…This requires a significant moment on each grain and the coupling can be reduced or even eliminated by a few atomic layers of Cr enriched alloy at the grain boundaries. These regions are typically Co 70 Cr 30 which is an AF composition indicating that AF materials do not show RKKY intergranular coupling [14]. Furthermore, from the contrast observed in bright and dark field TEM images it is clear that our samples are not crystallographically ordered and therefore, direct exchange coupling would not exist.…”

Section: Introductionmentioning

confidence: 92%

Antiferromagnetic grain volume effects in metallic polycrystalline exchange bias systems

Vallejo-Fernández¹,

Fernandez-Outon

O'Grady

2008

J. Phys. D: Appl. Phys.

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In this work we present a new interpretation of the role of the antiferromagnetic (AF) grain size in polycrystalline exchange bias thin films. It is found that at a finite temperature AF grains with sizes below a given critical volume VC do not contribute to the loop displacement because they are not thermally stable. There is a second critical volume VSET above which the AF grains cannot be set due to their anisotropy energy being too large. Therefore, only grains in the window between VC and VSET contribute to the loop displacement. Using this interpretation we can explain both the increase and the decrease in the exchange field with the AF grain size and the layer thickness.

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“…In ferromagnetic polycrystalline films, such as Co alloy recording media, intergranular exchange coupling occurs via an RKKY type mechanism. This requires a significant moment on each grain to polarise the conduction electrons and the coupling can be reduced or even eliminated by a few atomic layers of antiferromagnetic CoCr alloy at the grain boundary [44]. Hence, AF/AF coupling via an RKKY mechanism is known not to occur.…”

Section: Measurement Of K Afmentioning

confidence: 99%