Onset of metallic ferromagnetism in a doped spin-orbital chain

Abstract

Starting from a spin-orbital model for doped manganites, we investigate a competition between ferromagnetic and antiferromagnetic order in a one-dimensional model at finite temperature. The magnetic and orbital order at half filling support each other and depend on a small antiferromagnetic superexchange between t_{2g} spins and on an alternating Jahn-Teller potential. The crossover to a metallic ferromagnetic phase found at finite doping is partly suppressed by the Jahn-Teller potential which may localize e_g electrons.

6 pages, 4 figures, contribution to ICTP Ustron, 2004, see phys. stat. sol. at http://www.interscience.wiley.com