Role of Orbital Degeneracy in Double Exchange Systems

Abstract

We investigate the role of orbital degeneracy in the double exchange (DE) model. In the $J_H\to \infty$ limit, an effective generalized ``Hubbard'' model incorporating orbital pseudospin degrees of freedom is derived. The model possesses an exact solution in one- and in infinite dimensions. In 1D, the metallic phase off ``half-filling'' is a Luttinger liquid with pseudospin-charge separation. Using the $d=\infty$ solution for our effective model, we show how many experimental observations for the well-doped ($x\simeq 0.3$) three-dimensional manganites $L{a}_{1-x}S{r}_{x}Mn{O}_3$ can be qualitatively explained by invoking the role of orbital degeneracy in the DE model.

8 pages, 2 figures, submitted to Phys. Rev. B

References in corpus (3)

• Bosonization and Strongly Correlated Systems
• Temperature dependent scattering rate and optical mass of ferromagnetic metallic manganites
• Charge carrier density collapse in La_0.67Ca_0.33MnO_3 and La_0.67Sr_0.33MnO_3 epitaxial thin films

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