A Theory for Self-Trapped Magnetic Polaron in Ferromagnetic Semiconductor with a Narrow Band

Abstract

In a ferromagnetic semiconductor with a narrow band the mechanism which causes magnetization of localized spins around a conduction electron is similar to that of the double exchange interaction, and the potential which traps the conduction electron is a pseudopotential. It is shown that the spin flip processes of the conduction electron make the magnetic polaron unstable, and that even in the case of the narrow band limit the radius of the magnetic polaron is large extending over many lattice sites. These properties are different from those of the usual lattice polaron in narrow band.