High field magnetic study of small Fe particles dispersed in an alumina matrix

A high-field magnetic study has been performed on small Fe particles dispersed in an alumina matrix. The absolute value of the magnetic moment and its thermal variation are obtained. A reduction of its value is observed depending on the particle size. This behavior is caused mainly by particle surface magnetic disorders; the relative fraction of the perturbed atomic layers increases when the particle size decreases. It is concluded that the magnetization behavior of small particles in a high field can be explained on the basis of three contributions: two static terms corresponding to the magnetic moment of the nonrelaxing system and the effect of anisotropy and one fluctuating term related to the finite volume effect