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Phase Diagrams and Charge-Spin Separation in Two and Four Site Hubbard Clusters

Armen N. Kocharian·Gayanath W. Fernando·James W. Davenport
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Abstract

The charge spin-separation, pseudogap formation and phase diagrams are studied in two and four site Hubbard clusters using analytical diagonalization and grand canonical ensemble method in a multidimensional parameter space of temperature, magnetic field, on-site Coulomb interaction ($U\ge 0$), and chemical potential. The numerically evaluated, exact expressions for charge and spin susceptibilities provide clear evidence for the existence of true gaps in the ground state and pseudogaps in a limited range of temperature. In particular, Mott-Hubbard type charge crossover, spin pseudogap and magnetic correlations with antiferromagnetic (spin) pseudogap structure for two and four site clusters closely resemble the pseudogap phenomena and the normal-state phase diagram in high T$_c$ superconductors. ~ ~

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Armen N. Kocharian, Gayanath W. Fernando, James W. Davenport. 2005-10-23. Phase Diagrams and Charge-Spin Separation in Two and Four Site Hubbard Clusters. https://arxiv.org/abs/cond-mat/0510609

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