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 CuO 2 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 × 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.

Balzarotti, A., Cini, M., Perfetto, E., Stefanucci, G. (2004). W = 0 pairing in Hubbard and related models of low-dimensional superconductors. JOURNAL OF PHYSICS. CONDENSED MATTER, 16, 1387-1422 [10.1088/0953-8984/16/47/R01].

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

BALZAROTTI, ADALBERTO;CINI, MICHELE;Perfetto, E;STEFANUCCI, GIANLUCA
2004-01-01

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 CuO 2 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 × 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.
2004
Pubblicato
Rilevanza internazionale
Articolo
Sì, ma tipo non specificato
Settore FIS/03 - FISICA DELLA MATERIA
English
Con Impact Factor ISI
Carbon nanotubes; Ferromagnetism; Fullerenes; Hamiltonians; Mathematical models; Phonons; Theorem proving; Thermal effects; Distortions; Eigenstates; Hubbard models; On-site interactions; Superconducting materials
Balzarotti, A., Cini, M., Perfetto, E., Stefanucci, G. (2004). W = 0 pairing in Hubbard and related models of low-dimensional superconductors. JOURNAL OF PHYSICS. CONDENSED MATTER, 16, 1387-1422 [10.1088/0953-8984/16/47/R01].
Balzarotti, A; Cini, M; Perfetto, E; Stefanucci, G
Articolo su rivista
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2108/31218
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus ND
  • ???jsp.display-item.citation.isi??? 5
social impact