MAGNETIC-PROPERTIES OF HEISENBERG CLUSTERS

The effects of finite size on the thermodynamic properties of ferromag rietic clusters have been calculated on the basis of a self-consistent ly solved spin-wave spectrum for clusters of various sizes. The finite size leads to an effective power law for the temperature dependence o f the magnetization (M approximately T(alpha); 3/2 < alpha < 3), and t o a neutron-scattering cross section with a wavevector broadened discr ete spin-wave spectrum very different from that of the bulk. Predictio ns of the implications of finite size are extended to the size range o f nanoparticles. The effects should be readily observed in experiments .