Thermodynamic Properties of Spin Impurities in Heisenberg Ferromagnets

Abstract
Thermodynamic properties of an isolated spin impurity in a Heisenberg ferromagnet are calculated as functions of the magnitude of the impurity spin and of the strength of its exchange coupling to the host spins. The magnetization of the impurity, the energy and weight of its s-state localized mode (when one exists), and the shape of the local spectral weight function are all obtained as functions of temperature.