STERN-GERLACH DYNAMICS OF MAGNETIC CLUSTERS

A classical theory of the deflection of a single-domain ferromagnetic cluster in a Stern-Gerlach experiment is presented. Two cases are disc ussed in detail: (1) superparamagnetic relaxation, in which the therma l fluctuation of the cluster spin occurs on a time scale much smaller than the transit time of the cluster through the Stem-Gerlach apparatu s; and (2) anisotropy-induced relaxation, in which the cluster is suff iciently isolated from the thermal bath during its transit through the apparatus so that its dynamics is governed by the interaction of the cluster spin with the anisotropic magnetic forces caused by the lattic e and the shape of the cluster. Average spin orientation and average s pin rocking during transit, as well as Stem-Gerlach intensity profiles , are presented.