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arXiv:cond-mat/9908028 · Journal of Physics A Mathematical and General

The Fermion-ladder models: extensions of the Hubbard model with eta-pairing

Heng Fan

Published Nov 17, 1999• 10 citations
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Abstract

We propose two-leg fermion-ladder models for the SU (2|2) and SU (4) cases. The former is exactly the extended Hubbard model proposed by Essler, Korepin and Schoutens. The latter is a new model also with -pairing symmetry which is important for superconductivity. This new extension of the Hubbard model can be solved exactly.
DOI
10.1088/0305-4470/32/48/101

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For a simple Hubbard model, using a particle-particle pairing operator η and a particle-hole pairing operator ζ, it is shown that one can write down two commuting sets of angular momenta operators J and J′, both of which commute with the Hamiltonian. These considerations allow the introduction of quantum numbers j and j′ and lead to the fact that the system has SO 4=( SU 2× SU 2)/Z2 symmetry, j is related to the existence of superconductivity for a state and j′ to its magnetic properties.
For a simple Hubbard model, using a particle-particle pairing operator η and a particle-hole pairing operator ζ, it is shown that one can write down two commuting sets of angular momenta operators J and J′, both of which commute with the Hamiltonian. These considerations allow the introduction of quantum numbers j and j′, and lead to the fact that the system has SO 4 = ( SU 2 × SU 2)/ Z 2 symmetry. j is related to the existence of superconductivity for a state and j′ to its magnetic properties.