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تسجيل مستخدم جديدCompeting phases in the extended U-V-J Hubbard model near the van Hove fillings
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The phase diagram of the two-dimensional extended one-band U-V-J Hubbard model is considered within a mean-field approximation and two- and many-patch renormalization group (RG) approaches near the van Hove band fillings. At small t and J>0 mean-field and many-patch RG approaches give similar results for the leading spin-density-wave (SDW) instability, while the two-patch RG approach, which predicts a wide region of charge-flux (CF) phase becomes unreliable due to nesting effect. At the same time, there is a complex competition between SDW, CF phases, and d-wave superconductivity in two- and many-patch RG approaches. While the spin-flux (SF) phase is not stable at the mean-field level, it is identified as a possible ground state at J<0 in both RG approaches. With increasing t the results of all three approaches merge: d-wave superconductivity at J>0 and ferromagnetism at J<0 become the leading instabilities. For large enough V the charge-density-wave (CDW) state occurs.
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The paper is replaced by the extended version, cond-mat/0212190
Phase diagrams of the two-dimensional one-band t-t Hubbard model are obtained within the two-patch and the temperature-cutoff many-patch renormalization group approach. At small t and at van Hove band fillings antiferromagnetism dominates, while with
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