The phase diagram of the two-dimensional extended one-band (formula presented) 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 (formula presented) and (formula presented) mean-field and many-patch RG approaches give similar results for the leading spin-density-wave (SDW) instability, while the two-patch RG approach that predicts a wide region of charge-flux (CF) phase becomes unreliable due to nesting effect. There is a complex competition between SDW, CF phases, and d-wave superconductivity at small (formula presented) in two- and many-patch RG approaches. The spin-flux phase, which is not stable at the mean-field level, is identified as a possible ground state at (formula presented) in both RG approaches. With increasing (formula presented) the results of all three approaches merge: d-wave superconductivity at (formula presented) and ferromagnetism at (formula presented) become the leading instabilities. For large enough V, the charge-density-wave state occurs.
|Журнал||Physical Review B - Condensed Matter and Materials Physics|
|Состояние||Опубликовано - 2003|
|Опубликовано для внешнего пользования||Да|