Density of spin wave states in disordered Heisenberg ferromagnetic chains

Abstract

The density of spin wave states (DSWS) in disordered Heisenberg ferromagnetic chains, of which the exchange integrals are random quantities, is investigated. The DSWS is calculated by using the coherent potential approximation (CPA). The results are compared with Dean's (1959) exact numerical solutions for a finite chain. Although they are in good agreement at low impurity concentration, because of its mean field nature, the CPA is unable to reproduce the peaks occurring from impurity clustering at higher concentrations.