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The magnetocrystalline anisotropy energy of a ferromagnetic crystal can be expressed as a power series of direction cosines of the magnetic moment with respect to the crystal axes. The coefficient of those terms are the ''anisotropy constant''. In general the expansion is limited to few terms. Normally the magnetization curve is continuous respect to applied field up to saturation but, in certain intervals of the anisotropy constant values, irreversible field induced rotations of the magnetization are possible implying first order magnetization transition between equivalent magnetization minima, the so-called ''first order magnetization process'' (FOMP).〔''Handbook of Ferromagnetic materials, vol. 5'', eds K.H.J. Buschow and E.P. Wohlfarth; North-Holland, Amsterdam 1990〕 ==Theory== The ''total energy'' of an uniaxial magnetic crystal in an applied magnetic field can be written as a summation of the anisotropy term up to six order, neglecting the sixfold planar contribution, : and the field dependent Zeeman energy term : where: so the total energy can be written : 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「FOMP」の詳細全文を読む スポンサード リンク
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