Model exchange-spring nanocomposite magnetic grains

The magnetization reversal in nanocomposite two-phase grains embedded in a soft magnetic matrix is calculated using Brown's equation. The grains are spherical, consisting of a soft core surrounded by a hard shell. The calculation yields nonlinear algebraic expressions whose solutions describe the nucleation field as a function of the geometrical and magnetic parameters of the grains. The magnetization reversal depends not only on the total grain size but also on the shell thickness. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)