Quantum effects in double-exchange systems

Publisher Website
Google Scholar
Abstract
The stability of ferromagnetism in the s-d model of double exchange is investigated variationally for quantum spins. It is shown rigorously that for and infinite Hund's rule coupling, the state of complete spin alignment is unstable for 0.12 < n < 0.45, where n is the number of electrons per atom in the conduction band. Band narrowing in the paramagnetic state is also investigated in the quantum spin model. The effect is found to be somewhat stronger than in the classical spin limit and depends on n.