Existence of a novel metallic ferromagnetic phase in models for undoped manganites

Abstract

The existence of a novel metal-insulator transition in the ferromagnetic state of models for undoped manganites is here discussed using numerical techniques applied to the $e_{\mathrm{g}}$-orbital degenerate Hubbard model tightly coupled with Jahn-Teller distortions. The ground-state phase diagram is presented in the plane defined by the electron-phonon coupling $\lambda$ and Coulomb interaction $u$. In contrast to the standard one-band Hubbard model for cuprates, the metallic phase is found to exist for finite values of both $\lambda$ and $u$ in the present $e_{\mathrm{g}}$-orbital Hubbard model even at half-filling, due to the Fermi-surface topology which is incompatible with the staggered orbital ordering concomitant to the insulating phase. Based on the present results, a possible scenario for Colossal Magneto-Resistive effect is discussed in undoped manganites.

4 pages, Revtex, with 3 figures embedded in the text

References in corpus (3)

• Colossal Magnetoresistant Materials: The Key Role of Phase Separation
• Charge ordered ferromagnetic phase in La0.5Ca0.5MnO3
• Stripes Induced by Orbital Ordering in Layered Manganites

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