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W=0 pairing in Hubbard and related models of low-dimensional superconductors

Balzarotti, A; Cini, M; Perfetto, E and Stefanucci, Gianluca LU (2004) In Journal of Physics: Condensed Matter1990-01-01+01:00 16(47). p.1387-1422
Abstract
Lattice Hamiltonians with on-site interaction W have W = 0 solutions, that is, many-body singlet eigenstates without double occupation. In particular, W = 0 pairs give a clue to understand the pairing force in repulsive Hubbard models. These eigenstates are found in systems with high enough symmetry, like the square, hexagonal or triangular lattices. By a general theorem, we propose a systematic way to construct all the W = 0 pairs of a given Hamiltonian. We also introduce a canonical transformation to calculate the effective interaction between the particles of such pairs. In geometries appropriate for the CuO2 planes of cuprate superconductors, armchair carbon nanotubes, or cobalt oxide planes, the dressed pair becomes a bound state in a... (More)
Lattice Hamiltonians with on-site interaction W have W = 0 solutions, that is, many-body singlet eigenstates without double occupation. In particular, W = 0 pairs give a clue to understand the pairing force in repulsive Hubbard models. These eigenstates are found in systems with high enough symmetry, like the square, hexagonal or triangular lattices. By a general theorem, we propose a systematic way to construct all the W = 0 pairs of a given Hamiltonian. We also introduce a canonical transformation to calculate the effective interaction between the particles of such pairs. In geometries appropriate for the CuO2 planes of cuprate superconductors, armchair carbon nanotubes, or cobalt oxide planes, the dressed pair becomes a bound state in a physically relevant range of parameters. We also show that W = 0 pairs quantize the magnetic flux as superconducting pairs do. The pairing mechanism breaks down in the presence of strong distortions. The W = 0 pairs are also the building blocks for the antiferromagnetic ground state of the half-filled Hubbard model at weak coupling. Our analytical results for the 4 x 4 Hubbard square lattice, compared to available numerical data, demonstrate that the method, besides providing an intuitive grasp on pairing, also has quantitative predictive power. We also consider including phonon effects in this scenario. Preliminary calculations with small clusters indicate that vector phonons hinder pairing while half-breathing modes are synergic with the W = 0 pairing mechanism both at weak coupling and in the polaronic regime. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Physics: Condensed Matter1990-01-01+01:00
volume
16
issue
47
pages
1387 - 1422
publisher
IOP Publishing
external identifiers
  • wos:000225796800001
  • scopus:10344245529
ISSN
1361-648X
DOI
10.1088/0953-8984/16/47/R01
language
English
LU publication?
yes
id
95c75785-ce10-48e7-b58f-93ab13840614 (old id 258358)
date added to LUP
2007-10-16 16:08:02
date last changed
2017-01-01 07:22:58
@article{95c75785-ce10-48e7-b58f-93ab13840614,
  abstract     = {Lattice Hamiltonians with on-site interaction W have W = 0 solutions, that is, many-body singlet eigenstates without double occupation. In particular, W = 0 pairs give a clue to understand the pairing force in repulsive Hubbard models. These eigenstates are found in systems with high enough symmetry, like the square, hexagonal or triangular lattices. By a general theorem, we propose a systematic way to construct all the W = 0 pairs of a given Hamiltonian. We also introduce a canonical transformation to calculate the effective interaction between the particles of such pairs. In geometries appropriate for the CuO2 planes of cuprate superconductors, armchair carbon nanotubes, or cobalt oxide planes, the dressed pair becomes a bound state in a physically relevant range of parameters. We also show that W = 0 pairs quantize the magnetic flux as superconducting pairs do. The pairing mechanism breaks down in the presence of strong distortions. The W = 0 pairs are also the building blocks for the antiferromagnetic ground state of the half-filled Hubbard model at weak coupling. Our analytical results for the 4 x 4 Hubbard square lattice, compared to available numerical data, demonstrate that the method, besides providing an intuitive grasp on pairing, also has quantitative predictive power. We also consider including phonon effects in this scenario. Preliminary calculations with small clusters indicate that vector phonons hinder pairing while half-breathing modes are synergic with the W = 0 pairing mechanism both at weak coupling and in the polaronic regime.},
  author       = {Balzarotti, A and Cini, M and Perfetto, E and Stefanucci, Gianluca},
  issn         = {1361-648X},
  language     = {eng},
  number       = {47},
  pages        = {1387--1422},
  publisher    = {IOP Publishing},
  series       = {Journal of Physics: Condensed Matter1990-01-01+01:00},
  title        = {W=0 pairing in Hubbard and related models of low-dimensional superconductors},
  url          = {http://dx.doi.org/10.1088/0953-8984/16/47/R01},
  volume       = {16},
  year         = {2004},
}