THE MICROMAGNETICS OF CUBIC PARTICLES WITH CUBIC ANISOTROPY FAVORING BODY DIAGONAL MAGNETIZATION

Results of a numerical study of the micromagnetic configurations of mesoscopic cubic particles (side length L) for which the magnetocrystalline and configurational anisotropies conflict are reported. Using magnetic constants appropriate to nickel, it is found that in zero field stable flower states, symmetric about [111], exist for L less-than-or-equal-to 576 angstrom. For L greater-than-or-equal-to 540 angstrom, the ground state is a vortex, V100, about [100]. V111 and V110 states are also stable over limited ranges of particle size. The [100], [110] and [111] hysteresis loops are presented for particles having L = 300 and 780 angstrom. For the smaller particle the loops resemble those of Stoner and Wohlfarth (SW), but with a [110] switching field approximately 50% lower. For the 780 angstrom particle it is found that V100 persists in [100] fields with a switching field some ten times larger than that for SW. Both the [111] and [110] loops involve four state changes, with a very robust V100 configuration in low-fields.