Incommmensurability and unconventional superconductor to insulator transition in the hubbard model with bond-charge interaction.
We determine the quantum phase diagram of the one-dimensional Hubbard model with bond-charge interaction X in addition to the usual Coulomb repulsion U>0 at half-filling. For large enough X<t the model shows three phases. For large U the system is in the spin-density wave phase as in the usual Hubbard model. As U decreases, there is first a spin transition to a spontaneously dimerized bond-ordered wave phase and then a charge transition to a novel phase in which the dominant correlations at large distances correspond to an incommensurate singlet superconductor.
Aligia
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AA
Comisión Nacional de Energía Atómica, Centro Atómico Bariloche and Instituto Balseiro, 8400 S.C. de Bariloche, Argentina.
Anfossi
A
A
Arrachea
L
L
Degli Esposti Boschi
C
C
Dobry
A O
AO
Gazza
C
C
Montorsi
A
A
Ortolani
F
F
Torio
M E
ME