1999/09/30 by Masaaki Nakamura · 3 citations
Materials Science · Physics and Astronomy · #Charge density wave #Condensed matter physics #Hubbard model #Organic and Molecular Conductors Research #Phase (matter) #Phase diagram #Physics #Physics of Superconductivity and Magnetism #Quantum and electron transport phenomena #Quantum mechanics #Renormalization group #Superconductivity #Tricritical point #cond-mat.stat-mech #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.61.16377
published as Phys. Rev. B 61 (2000) 16377 · 18 pages(REVTeX), 17 figures(EPS(color)), 3 tables, Detailed paper of JPSJ 68 (1999) 3123 (cond-mat/9903227), see also cond-mat/0003419
openalex publication_date 2000/06/15 · arxiv created 2000/07/16 · arxiv updated 2016/08/31 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Phase diagrams of the one-dimensional extended Hubbard model (including nearest-neighbor interaction V) at half- and quarter-filling are studied by observing level crossings of excitation spectra using the exact diagonalization. This method is based on the Tomonaga-Luttinger liquid theory including logarithmic corrections which stem from the renormalization of the Umklapp- and the backward-scattering effects. Using this approach, the phase boundaries are determined with high accuracy, and then the structure of the phase diagram is clarified. At half-filling, the phase diagram consists of two Berezinskii-Kosterlitz-Thouless (BKT) transition lines and one Gaussian transition line in the charge sector, and one spin-gap transition line. This structure reflects the U(1)\ensuremath\bigotimesSU(2) symmetry of the electron system. Near the U=2V line, the Gaussian and the spin-gap transitions take place independently from the weak- to the intermediate-coupling region, but these two transition lines are coupled in the strong-coupling region. This result demonstrates existence of a tricritical point and a bond-charge-density-wave (BCDW) phase between charge- and spin-density-wave (CDW, SDW) phases. To clarify this mechanism of the transition, we also investigate effect of a correlated hopping term, which plays a role to enlarge BCDW and bond-spin-density-wave (BSDW) phases. At quarter-filling, a similar crossover phenomenon also takes place in the large-V region involving spin-gap and BKT-type metal-insulator transitions.