2005/10/10 by Satoru Odashima, Adolfo Avella, Ferdinando Mancini · 1 citation
Physics and Astronomy · #Cold Atom Physics and Bose-Einstein Condensates #Condensed matter physics #Hubbard model #Physics #Physics of Superconductivity and Magnetism #Quantum and electron transport phenomena #Quantum mechanics #Quasiparticle #cond-mat.str-el #t-J model
paper · pdf · doi:10.1103/physrevb.72.205121
published as Phys. Rev. B 72, 205121 (2005) · 13 pages, 8 figures
arxiv created 2005/10/10 · openalex publication_date 2005/11/18 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
The electronic states of the two-dimensional Hubbard model are investigated by means of a 4-pole approximation within the composite operator method. In addition to the conventional Hubbard operators, we consider other two operators which come from the hierarchy of the equations of motion and carry information regarding nearest-neighbor spin and charge configurations. By means of this operatorial basis, we can study the physics related to the energy scale of J=4t2∕U in addition to the one of U. Present results show relevant physical features, well beyond those previously obtained by means of a 2-pole approximation, such as a four-band structure with shadow bands and a quasiparticle peak at the Fermi level. The Fermi level stays pinned to the band flatness located at (\ensuremathπ,0)-point within a wide range of hole-doping (0\ensuremath\leqslant\ensuremathδ\ensuremath\leqslant0.15). A comprehensive analysis of double occupancy, internal energy, specific heat and entropy features have also been performed. All reported results are in excellent agreement with the data of numerical simulations.