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Charge ordering and phase separation in the infinite dimensional extended Hubbard model

Ning-Hua Tong·Shun-Qing Shen·Ralf Bulla
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Abstract

We study the extended Hubbard model with both on-site (U) and nearest neighbor (V) Coulomb repulsion using the exact diagonalization method within the dynamical mean field theory. For a fixed U (U=2.0), the T-n phase-diagrams are obtained for V=1.4 and V=1.2, at which the ground states of n=1/2 system is charge-ordered and charge-disordered, respectively. In both cases, robust charge order is found at finite temperature and in an extended filling regime around n=1/2. The order parameter changes non-monotonously with temperature. For V=1.4, phase separation between charge-ordered and charge-disordered phases is observed in the low temperature and n < 0.5 regime. It is described by an "S"-shaped structure of the n-/mu curve. For V=1.2, the ground state is charge-disordered, and a reentrant charge-ordering transition is observed for 0.42 < n < 0.68. Relevance of our results to experiments for doped manganites is discussed.

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Ning-Hua Tong, Shun-Qing Shen, Ralf Bulla. 2004-03-06. Charge ordering and phase separation in the infinite dimensional extended Hubbard model. https://doi.org/10.1103/physrevb.70.085118

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