Abstract:
The Heisenberg model at low temperatures and with nonmagnetic substitutional
impurities is investigated. The coherent potential method and the properties
of a percolation cluster are used. The proposed method of making the
solutions self-consistent creates a unified theoretical scheme in which
expressions can be obtained for the stiffness coefficient of the spin waves
and for the magnetization both at low impurity concentrations and nearly
critical concentrations. The region of applicability of the obtained
expressions is investigated.