W=0 pairing in Hubbard and related models of lowdimensional superconductors
(2004) In Journal of Physics: Condensed Matter19900101+01:00 16(47). p.13871422 Abstract
 Lattice Hamiltonians with onsite interaction W have W = 0 solutions, that is, manybody 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 onsite interaction W have W = 0 solutions, that is, manybody 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 halffilled 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 halfbreathing modes are synergic with the W = 0 pairing mechanism both at weak coupling and in the polaronic regime. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/record/258358
 author
 Balzarotti, A; Cini, M; Perfetto, E and Stefanucci, Gianluca ^{LU}
 organization
 publishing date
 2004
 type
 Contribution to journal
 publication status
 published
 subject
 in
 Journal of Physics: Condensed Matter19900101+01:00
 volume
 16
 issue
 47
 pages
 1387  1422
 publisher
 IOP Publishing
 external identifiers

 wos:000225796800001
 scopus:10344245529
 ISSN
 1361648X
 DOI
 10.1088/09538984/16/47/R01
 language
 English
 LU publication?
 yes
 id
 95c75785ce1048e7b58f93ab13840614 (old id 258358)
 date added to LUP
 20071016 16:08:02
 date last changed
 20170101 07:22:58
@article{95c75785ce1048e7b58f93ab13840614, abstract = {Lattice Hamiltonians with onsite interaction W have W = 0 solutions, that is, manybody 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 halffilled 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 halfbreathing 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 = {1361648X}, language = {eng}, number = {47}, pages = {13871422}, publisher = {IOP Publishing}, series = {Journal of Physics: Condensed Matter19900101+01:00}, title = {W=0 pairing in Hubbard and related models of lowdimensional superconductors}, url = {http://dx.doi.org/10.1088/09538984/16/47/R01}, volume = {16}, year = {2004}, }