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Role of Orbital Degeneracy in Double Exchange Systems

M. S. Laad·L. Craco·E. Müller-Hartmann
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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 $La_{1-x}Sr_{x}MnO_{3}$ can be qualitatively explained by invoking the role of orbital degeneracy in the DE model.

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M. S. Laad, L. Craco, E. Müller-Hartmann. 2000-07-11. Role of Orbital Degeneracy in Double Exchange Systems. https://doi.org/10.1103/physrevb.63.214419

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