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Computational Micromagnetism of Magnetic Structures and Magnetization Processes in Thin Platelets and Small Particles

  • H. Kronmüller
  • R. Hertel
Part of the NATO Science Series book series (NAII, volume 41)

Abstract

The micromagnetic background for the investigation of magnetic configurations in thin platelets and small particles by means of the Finite Element Method is discussed. It is shown that in thin rectangular platelets high remanence and low remanence configurations may exist.

The configurations of lowest magnetic energy are the Landau structure with cross-tie wall and the diamond structure. The magnetization process of these configurations takes place by reversible spin rotations and domain wall displacements. Intrinsic irreversible magnetization processes are related to the annihilation of domain walls and the displacement of the domain walls to the particle edges. The coercive field is found to correspond approximately to the demagnetization field of the homogeneously magnetized platelet.

In cubic particles it is shown that with increasing edge length the configurations with lowest energy change from the so-called Flower State via the Twisted Flower State to the Vortex State. For a composite system of hard and soft magnetic particles the hysteresis loops and the coercive fields are determined in dependence of the diameter of the soft particle. It turns out that the magnetically soft particles reduce the coercive field of the hard phase for diameters > 2.5 ͔B of the hard phase.

Keywords

Domain Wall Coercive Field Soft Particle Closure Domain Magnetization Process 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. 1.
    R Street & J C Wooley. Proc. Phys. Soc., A62 562 (1949)Google Scholar
  2. 2.
    L Neel. Ann. Geophys, 5 99 (1949)Google Scholar
  3. 3.
    W F Brown Jr. Phys. Rev., 100 1677 (1963)CrossRefGoogle Scholar
  4. 4.
    W F Brown Jr., IEEE Trans. Mag. 15 1196 (1979)CrossRefGoogle Scholar
  5. 5.
    A Aharoni. Phys. Rev. A135 447 (1964)CrossRefGoogle Scholar
  6. 6.
    Thermal relaxation is extensively reviewed in: A Aharoni.’ Introduction to the theory of Ferromagnetism’ (Clarendon Press, Oxford 1996)Google Scholar
  7. 7.
    W T Coffey, D S J Crothers, J L Dormann, L J Geoghegan, Yu P Kalmykov, J T Waldron & A W Wickstead. Phys. Rev. B52 15951 (1995)Google Scholar
  8. 8.
    R W Chantrell, J D Hannay, M Wongsam, T Schrefl and H-J Richter. IEEE Trans. Mag. 34 1839 (1998)CrossRefGoogle Scholar
  9. 9.
    L D Landau & E M Lifshitz. ‘Statistical Physics’ (Oxford: Pergammon 1980)Google Scholar
  10. 10.
    H B Callen & T A Welton. Phys. Rev., 83 34 (1951)Google Scholar
  11. 11.
    R W Chantrell & J D Hannay, J. Mag. Soc. Japan. 21 Suppl. 52 283 (1997)Google Scholar
  12. 12.
    W D Doyle & L He, IEEE Trans. Mag. 29 3649 (1993)CrossRefGoogle Scholar
  13. 13.
    C P Hancock, K O’Grady & M el-Hilo. J. Phys. D: Applied Physics 29 2343 (1996)CrossRefGoogle Scholar
  14. 14.
    A Lyberatos & R W Chantrell. J. Appl. Phys. 73 6501 (1993)CrossRefGoogle Scholar
  15. 15.
    W Cheng, S Zhang & H N Bertram. J. Appl. Phys. 71 5579 (1992)CrossRefGoogle Scholar
  16. 16.
    Y Nakatani, Y Uesaka, N Hayashi & H Fukushima. J. Magn. Magn. Mater., 168 347 (1997)CrossRefGoogle Scholar
  17. 17.
    E D Boerner & H N Bertram. IEEE Trans, mag. 33 3052 (1997)CrossRefGoogle Scholar
  18. 18.
    M Wongsam & R W Chantrell. Submitted for publicationGoogle Scholar
  19. 19.
    M Lederman, S Schultz & M Ozaki. Phys. Rev. Lett. 73 1986 (1994)CrossRefGoogle Scholar
  20. 20.
    O Chubykalo et al, to be publishedGoogle Scholar
  21. 21.
    H. N. Bertram and Q. Peng, IEEE Trans. Magn., 34(4), 1543 (1998).CrossRefGoogle Scholar
  22. 22.
    J D Hannay, R.W Chantrell and H-J Richter, J. Appl. Phys 85, 5012–5014(1999)CrossRefGoogle Scholar
  23. 23.
    N. S. Walmsley, C. Dean, A. Hart and D. A. Parker, IEEE Trans. Magn., 30(6), 4362 (1994).CrossRefGoogle Scholar
  24. 24.
    H-J. Richter and R. Ranjan, J. Magn. Magn. Mater. (Submitted).Google Scholar
  25. 25.
    V. G. Baryakhtar, B. A. Ivanov, A. L. Sukstanskii and E. Y. Melikhov, Phys. Rev B. 56(2), 619 (1997).CrossRefGoogle Scholar
  26. 26.
    W.D. Doyle, S. Stinnett, C. Dawson and L. He, J. Magn. Soc. Japan. 22, No.3, 91 (1998).Google Scholar
  27. 27.
    Y. Yu and J. W. Harrell, J. Magn. Magn. Mater., 155, 126 (1996).CrossRefGoogle Scholar
  28. 28.
    C H Back et al Science August 5th 1999Google Scholar
  29. 29.
    P Lu and S H Charap. IEEE Trans Mag 30 4230 (1994)CrossRefGoogle Scholar
  30. 30.
    P Gaunt, J. Appl. Phys., 59 4129 (1986)CrossRefGoogle Scholar
  31. 31.
    E P Wohlfarth, J Phys. F: Met. Phys., 14 2155 (1984)CrossRefGoogle Scholar
  32. 32.
    A Lyberatos and R W Chantrell, J. Phys. Condens. Matter, 9 2623 (1997)CrossRefGoogle Scholar
  33. 33.
    E C Stoner and E P Wohlfarth, Phil. Trans. Roy. Soc., A240 559 (1948)Google Scholar
  34. 34.
    G.N Coverdale, R.W Chantrell and K O’Grady, J Magn. Magn. Mater, 83, 442, (1990)CrossRefGoogle Scholar
  35. 35.
    D K Lottis, E.D Dahlberg, J.A Christner, J.I Lee, R.L Peterson and R.M White, J Appl. Phys., 63, 2920 (1990)CrossRefGoogle Scholar
  36. 36.
    Y Uesaka, Y Nakatani and N Hayashi, J Magn. Magn. Mater, (in press)Google Scholar
  37. 37.
    Y Hosoe, T Kanbe, K Tanahashi, I Tamai, S Matsunuma and Y Tanahashi, IEEE Trans. Mag., 34, 1528 (1998)CrossRefGoogle Scholar
  38. 38.
    H Gong, W Yang and D Lambeth, IEEE Trans Mag, 34, 1612 (1998)CrossRefGoogle Scholar
  39. 39.
    E.N Abarra, P Glijer, H Kisker, I Okamoto and T Suzuki, J. Magn. Magn. Mater., 175, 148 (1997)CrossRefGoogle Scholar
  40. 40.
    H.J Richter, IEEE Trans. Mag 35, 2790 (1999)CrossRefGoogle Scholar
  41. 41.
    M Alex and D Wachenschwantz, IEEE Trans. Mag 35, 2796 (1999)CrossRefGoogle Scholar
  42. 42.
    M Futamoto, Y Hirayama, N Inaba, Y Honda, K Ito, A Kikugawa and T Takeuchi, IEEE Trans. Mag 35, 2802 (1999)CrossRefGoogle Scholar
  43. 43.
    A Moser and D Weller, IEEE Trans. Mag 35, 2808 (1999)CrossRefGoogle Scholar
  44. 44.
    R.W. Chantrell, A. Lyberatos and E.P. Wohlfarth, J. Phys. F. 16, L145 (1986).CrossRefGoogle Scholar
  45. 45.
    D.K. Lottis, E.H. Dahlberg, J.A. Christner, J.I. Lee, R.L. Peterson and R.M. White, J. Appl. Phys. 63 2920 (1988).CrossRefGoogle Scholar
  46. 46.
    Y. Kanai and S.H. Charap, IEEE Trans MAG-27, 4972 (1991).Google Scholar
  47. 47.
    K Binder, ‘Monte Carlo methods in statistical physics’ (Springer, Berlin, 1979) p33CrossRefGoogle Scholar
  48. 48.
    U Nowak, R.W Chantrell and E.C Kennedy, Phys Rev. Lett., 84, 163 (2000)CrossRefGoogle Scholar
  49. 49.
    J M Gonzales, R Ramirez, R Smirnov-Rueda and J Gonzalez, Phys. Rev. B 52 16034 (1995)CrossRefGoogle Scholar
  50. 50.
    A Lyberatos, D.V Berkov and R.W Chantrell, J Phys. Condens. Matter 5, 8911 (1993)CrossRefGoogle Scholar
  51. 51.
    W.T. Coffey, D.S.F. Crothers, J.L. Dormann, L.J. Geoghegan, and E.C. Kennedy, Phys. Rev. B 58 3249 (1998).CrossRefGoogle Scholar
  52. 52.
    W.T. Coffey, D.S.F. Crothers, J.L. Dormann, Yu. P. Kalmykov, E.C. Kennedy, W. Wernsdorfer, Phys. Rev. Lett. 80 5655 (1998).CrossRefGoogle Scholar
  53. 53.
    O Chubykalo, B. Lengsfield, B. Jones, J. Kaufman, J.M. Gonzalez, R.W. Chantrell and R. Smirnov-Rueda, J Magn. Magn. Mater (in press)Google Scholar
  54. 54.
    R. Smimov-Rueda, O. Chubykalo, R.W. Chantrell and J.M. Gonzalez, MMM’99 Conference J. Appl. Phys (in press).Google Scholar
  55. 55.
    B. Lengsfield, O. Chubykalo, J. Kaufinan, B. Jones, MMM’99 Conference (abstract AE-15), to be published.Google Scholar

Copyright information

© Springer Science+Business Media Dordrecht 2001

Authors and Affiliations

  • H. Kronmüller
    • 1
  • R. Hertel
    • 1
  1. 1.Max-Planck-Institut für MetallforschungStuttgartGermany

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