Onset of metallic ferromagnetism in a doped spin-orbital chain

TL;DR

This paper studies how doping influences magnetic phases in a one-dimensional spin-orbital model relevant to manganites, revealing a complex interplay between ferromagnetism, antiferromagnetism, and electron localization effects.

Contribution

It introduces a detailed finite-temperature analysis of magnetic and orbital order competition in a doped spin-orbital chain, highlighting the role of Jahn-Teller effects and superexchange interactions.

Findings

Magnetic and orbital orders support each other at half filling.

Jahn-Teller potential can localize electrons, suppressing metallic ferromagnetism.

Finite doping induces a crossover to a metallic ferromagnetic phase.

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.