Magnetic anisotropy, first-order magnetization process and the Brown paradox in rare-earth compounds

Anomalous behavior of magnetization curves in rare-earth compounds is considered. It is shown that the explanation of this effect due to the large values of magnetic anisotropy constants K-i of higher order contradicts the point charge approximation of the crystal field theory. An alternative approach within the framework of sublattice model and first-order magnetic anisotropy constants k(1) only is proposed. The sublattice values of k(1) are taken from independent nuclear magnetic resonance data. The direct calculation leads to satisfactory explanation of experiment in Tb-2 Fe-17 crystal. In conclusion, a possible relation of first-order magnetization process and Brown paradox in coercivity and domain structure is discussed. (C) 2002 Elsevier Science B.V. All rights reserved.