Phase diagram of the extended hubbard model with pair hopping interaction |
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Authors: | GI Japaridze S Sarkar |
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Institution: | Max-Planck-Institut für Physik komplexer Systeme, N?thnitzer Str. 38, 01187, Dresden, Germany, DE Institute of Physics, Georgian Academy of Sciences, Tamarashvili Str. 6, 380077, Tbilisi, Georgia, GE
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Abstract: | A one-dimensional model of interacting electrons with on-site U, nearest-neighbor V, and pair-hopping interaction W is studied at half-filling using the continuum limit field theory approach. The ground state phase diagram is obtained for
a wide range of coupling constants. In addition to the insulating spin-density wave (SDW) and charge-density wave (CDW) phases
for large U and V, respectively, we identify a bond-charge-density-wave (BCDW) phase W < 0, | U - 2V| < | 2W| and a bond-spin-density-wave (BSDW) for W > 0, | U - 2V| < W. The possibility of bond-located ordering results from the site-off-diagonal nature of the pair-hopping term and is a special
feature of the half-filled band case. The BCDW phase corresponding to an enhanced Peierls instability in the system. The BdSDW
is an unconventional insulating magnetic phase, characterized by a gapless spin excitation spectrum and a staggered magnetization
located on bonds between sites. The general ground state phase diagram including insulating, metallic, and superconducting
phases is discussed. A transition to the η-superconducting phase at | U - 2V| ≪ 2t?W is briefly discussed.
Received 20 February 2002 / Received in final form 11 April 2002 Published online 19 July 2002 |
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Keywords: | PACS 71 27 +a Strongly correlated electron systems heavy fermions – 71 10 Hf Non-Fermi-liquid ground states electron phase diagrams and phase transitions in model systems – 71 10 Fd Lattice fermion models (Hubbard model etc ) |
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