Time dependence in perpendicular media with a soft underlayer

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Dutson, J D ; Wu, J ; O'Grady, K ; Woolsey, N C ; Kubota, Y ; Platt, C L (2004)

In this paper we describe measurements of magnetic viscosity or time dependence in magnetic thin films suitable for use as perpendicular recording media. Generally, such effects cannot be measured using conventional magnetometry techniques due to the presence of a thin (0.1 mum) soft underlayer (SUL) in the media necessary to focus the head field. To achieve our results we have developed an ultrastable MOKE magnetometer, the construction of which is described. This has enabled us to measure nominally identical films with and without the presence of the SUL. We find that the presence of the SUL narrows the energy barrier distribution in the perpendicular film increasing the nucleation field (H-n), reducing the coercivity (H-c) and results in an increase in the squareness of the loop. This in turn results in an increase in the magnitude of the viscosity in the region of the H-c but that the range of fields over which the viscosity occurs is reduced.
  • References (7)

    [1] R. Wood, J. Miles, and T. Olson, “Recording technologies for terabit per square inch systems,” IEEE Trans. Magn., vol. 38, pp. 1711-1718, July 2002.

    [2] K. O'Grady, P. Dova, and H. Laidler, “Determination of critical volumes in recording media,” in Mater. Res. Soc. Proc., vol. 517, 1998, pp. 231-242.

    [3] R. Street and J. C. Woolley, “A study of magnetic viscosity,” in Proc. Phys. Soc., vol. A62, 1949, pp. 562-572.

    [4] M. El Hilo, K. O'Grady, R. W. Chantrell, and D. P. E. Dickson, “Time dependent magnetization in systems with distributed energy barriers,” J. Magn. Magn. Mater., vol. 123, pp. 30-34, 1993.

    [5] K. Le Phan and C. Lodder, “Iterative method for intrinsic viscosity measurements on perpendicular recording media,” IEEE Trans Magn., vol. 38, pp. 2003-2005, Sept. 2002.

    [6] J. Wu, L. Holloway, H. Laidler, K. O'Grady, S. Khizroev, J. K. Howard, R. W. Gustafson, and D. Litvinov, “Magnetic characterization of perpendicular recording media,” IEEE Trans. Magn., vol. 38, pp. 1682-1686, July 2002.

    [7] J. D. Dutson, K. O'Grady, B. Lu, Y. Kubota, and C. L. Platt, “Determination of activation volumes of reversal in perpendicular media,” IEEE Trans Magn., vol. 39, pp. 2344-2346, Sept. 2003.

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