The "W=0" Pairing Mechanism from Repulsive Interactions in Symmetric 2d Models
| dc.creator | Cini, Michele | |
| dc.creator | Stefanucci, Gianluca | |
| dc.date | 2002-04-15 | |
| dc.date.accessioned | 2026-07-07T02:45:03Z | |
| dc.date.available | 2026-07-07T02:45:03Z | |
| dc.description | In two-dimensional systems possessing a high degree of symmetry, the repulsive electron-electron interaction produces a pairing force; the mechanism would fail in the presence of strong distortions. We have studied this in the one-band and three-band Hubbard Model. From partially occupied orbitals one obtains pair eigenstates of the Hamiltonian with no on-site repulsion (the W=0 pairs). The concept of W=0 pairs allows to make qualitative and quantitative predictions about the behaviour of interacting many-body systems, a quite remarkable and unusual situation. Exact numerical solutions for clusters with ``magic'' hole numbers reveal attraction between the holes in W=0 pairs. The effect occurs in all fully symmetric clusters which are centered on a Cu site; then holes get paired in a wide, physically relevant parameter range and show superconducting quantization of the magnetic flux. A canonical transformation of the Hamiltonian, valid for clusters and for the full plane, leads to a Cooper-like equation for the W=0 pairs. We have evaluated the effective interaction and found that W=0 pairs are the bare quasiparticles which, once dressed, become two-hole bound states. We applied the above theory to the doped antiferromagnet, and found that the ground state at half filling is the singlet component of a determinantal state. We write down this determinant and the ground state wave function explicitly in terms of a many-body W=0 eigenstate. Our analytical results for the $4\times 4$ square lattice at half filling and with doped holes, compared to available numerical data, demonstrate that the method, besides providing intuitive grasp on pairing, also has quantitative predictive power. | |
| dc.description | 33 pages, 9 figures, contribution to "Electrons and Photons in Solids, A Volume in Honour of Franco Bassani" | |
| dc.identifier | https://arxiv.org/abs/cond-mat/0204311 | |
| dc.identifier | http://arxiv.org/abs/cond-mat/0204311 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/19171 | |
| dc.subject | Superconductivity | |
| dc.subject | Strongly Correlated Electrons | |
| dc.title | The "W=0" Pairing Mechanism from Repulsive Interactions in Symmetric 2d Models | |
| dc.type | text |