Ferromagnetism in Electronic Models for Manganites

Abstract

Ground state properties of the Kondo model for manganese oxides in one dimension are studied using numerical techniques. The large Hund coupling ($J_H$) limit is specially analyzed. A robust region of fully saturated ferromagnetism (FM) is identified at all densities. For open boundary conditions it is shown exactly that the ground state is FM at $J_H=\infty$. Hole-spin phase separation competing with FM was also observed when a large exchange $J$ between the $M{n}^{3+}$ ions is used. As the spin of the transition metal ion grows, the hole mobility decreases providing a tentative explanation for the differences between Cu-oxides and Mn-oxides.

4 pages with 3 figures embedded in the text, Submitted for publication on August 20, 1996, Minor changes