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List of Figures

  1. William Gilbert's magnetic model of the Earth
  2. Coulomb's dipoles and Faraday's lines of force
  3. An exploded view of the Hitachi Microdrive
  4. Increasing storage density
  5. A three-platter IDE hard disk drive, manufactured by Fujitsu in 1999
  6. Energy density due to uniaxial anisotropy
  7. Cubic anisotropy energy surfaces
  8. The unit vectors of two moments $ \ensuremath{\mathbf{S}}_i$ and $ \ensuremath{\mathbf{S}}_j$
  9. The functions $ \cos{\phi}$ and $ 1-{\phi ^2 \over 2}$
  10. The effect of altering the number of cells in a geometry
  11. Finite difference and finite element meshes
  12. Relaxed magnetisation from edge- and diagonally-aligned states
  13. Typical hysteresis loops
  14. Magnetic recording ideals
  15. A typical ferromagnet
  16. Domains formed in sample with closed flux
  17. Micromagnetic system states
  18. The simplified simulation process
  19. OOMMF memory requirements
  20. Memory usage scaling with magpar
  21. Memory usage of OOMMF and magpar
  22. A visualisation showing surface maps, streamlines, magnetisation and an isosurface
  23. Massless particles highlighting core vortex
  24. Out-of-plane and in-place vortices
  25. Patterned and non-patterned media
  26. Magnetoresistive random access memory
  27. Single-domain and vortex states
  28. Anisotropic simulation domain
  29. Hysteresis loop for a flat nickel cylinder
  30. Cylinder overview with magnetisation in a high applied field
  31. Magnetisation in flat cylinder
  32. Flower state and onion state in a cylinder
  33. Flat cylinder entering the vortex state
  34. Flat cylinder just before leaving the vortex state
  35. Height dependence of state transition in cylinders
  36. Phase diagram for nickel cylinders
  37. Hysteresis loops for nickel spheres of diameter $ d$=200nm
  38. Nickel sphere in high applied field showing spin tapering
  39. Sphere at high applied field
  40. Sphere immediately after entering the vortex state
  41. Sphere in vortex state
  42. Sphere in late vortex state
  43. Size dependence of nickel spheres
  44. Hysteresis loops for nickel spheres of diameter 50nm and 80nm
  45. Remanent magnetisation states in conical geometries
  46. Phase diagram of remanent states in cones
  47. Hysteresis loop for cone of $ d=h=$100nm
  48. Detailed points for cone reversal mechanism where $ d=h=$100nm
  49. Scanning electron microscope image of a droplet array
  50. MOKE measurements for a nickel dot array
  51. The double-template self-assembly technique
  52. A typical nanodot ``droplet'' geometry
  53. Hysteresis loop for a nickel half-sphere of diameter 200nm
  54. Half-sphere at high applied field (point $ a$ in figure 5.5)
  55. Half-sphere in remanent vortex state
  56. Half-sphere in late vortex state
  57. Reversal mechanism phase diagram for part-spheres
  58. Reversal mechanism for $ d$=50nm, $ h$=0.5$ d$
  59. Reversal mechanism for $ d$=100nm, $ h$=$ d$
  60. Hysteretic comparison of OOMMF (FD method) and magpar (hybrid FE/BE method)
  61. Hysteresis loop for an isotropic nickel half-sphere of diameter 350nm
  62. Two vortex states in an isotropic nickel half-sphere of diameter 350nm
  63. Hysteresis loop for isotropic nickel half-sphere of diameter 750nm
  64. Vortex ``pinning'' in three-quarter sphere
  65. Reversal mechanism for nickel droplet of diameter 140nm
  66. Hysteresis loops for droplets of bounding sphere diameter 140nm, 350nm and 500nm
  67. Size dependence of coercive field in droplet nanodots
  68. Comparison of experiment and simulation for nickel nanodots
  69. Different hysteresis characteristics in droplet nanodots
  70. Reversal mechanism of a droplet in a perpendicular applied field
  71. Size dependence of out-of-plane coercive field in droplet nanodots
  72. Size dependence of out-of-plane and in-plane coercivity in droplet nanodots
  73. The single-template self-assembly technique
  74. Scanning electron microscope image of an antidot array
  75. Oscillation of coercivity observed experimentally
  76. Cubically and hexagonally packed spheres
  77. 600x600x150nm cut of simple cubic nickel antispheres
  78. Magnetisation of a cobalt hexagonal antidot array in zero field
  79. Hysteresis loop for permalloy antidot array
  80. Microscopic images of an antidot array
  81. Measured and computed demagnetising field of an antidot array in zero field
  82. Measured and computed MFM signal of an antidot sample in a small applied field
  83. Overview of Monte Carlo simulation
  84. Coercivity of small permalloy nanodots
  85. Coercivity of large permalloy nanodots
  86. Monte Carlo simulation results
  87. MOKE and numerical measurements for cobalt antidots
  88. Polar plot of anisotropy energy and reversal conditions
  89. The complete simulation process
  90. The OOMMF Oxs framework
  91. Simple constructive solid geometries


Richard Boardman 2006-11-28