Off-Diagonal Long-Range Order in Generalized Hubbard Models

Michielsen, Kristel; Raedt, Hans De

doi:10.1142/s021797929700068x

Cited by 10 publications

(6 citation statements)

References 26 publications

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“…While the values of K ρ alone cannot distinguish between singlet s-wave (even) and triplet p-wave (odd) superconducting states, the BCS results and the Berry phases (0,0) are indicative of the former. A demonstration of the s-wave character was provided by the results of stochastic diagonalization by Michielsen and De Raedt 46 which showed the presence of singlet-singlet quasi ODLRO in 1D for t AA = 1, t AB = 1.4 and t BB = 1.8, n = 1.5 and U < 1, and also for t AA = t AB = t BB = 1, U = −4 and n = 1.5 (negative-U Hubbard model).…”

Section: S -Wave Superconductivitymentioning

confidence: 99%

Superconductivity with s and p symmetries in an extended Hubbard model with correlated hopping

et al. 1998

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We consider a generalized Hubbard model with on-site and nearest-neighbour repulsions U and V respectively, and nearest-neighbour hopping for spin up (down) which depends on the total occupation n b of spin down (up) electrons on both sites involved. The hopping parameters are tAA, tAB and tBB for n b = 0, 1, 2 respectively. We briefly summarize results which support that the model exhibits s-wave superconductivity for certain parameters and extend them by studying the Berry phases. Using a generalized Hartree-Fock(HF) BCS decoupling of the two and three-body terms, we obtain that at half filling, for tAB < tAA = tBB and sufficiently small U and V the model leads to triplet p-wave superconductivity for a simple cubic lattice in any dimension. In one dimension, the resulting phase diagram is compared with that obtained numerically using two quantized Berry phases (topological numbers) as order parameters. While this novel method supports the previous results, there are quantitative differences.

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Section: S -Wave Superconductivitymentioning

confidence: 99%

Superconductivity with s and p symmetries in an extended Hubbard model with correlated hopping

et al. 1998

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“…11,21,57 In the case of ODLRO this susceptibility χ (V ) sym must increase with the system size L and must scale to infinity for the infinite system size L = ∞ (Fig. 6).…”

Section: Finite Size Scaling In the Bcs-reduced Hubbard Modelsmentioning

confidence: 99%

Finite Size Scaling in the tt'-Hubbard Model and in BCS-Reduced Hubbard Models

Fettes

Morgenstern

1998

Int. J. Mod. Phys. C

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With the projector quantum Monte Carlo algorithm and the stochastic diagonalization it is possible to calculate the ground state of the Hubbard model for small finite clusters. Nevertheless the usual finite size scaling of the Hubbard model has problems of deducing the behavior of the infinite system correctly from the numerical data of small system sizes. Therefore we study the finite size scaling of the superconducting correlation functions in superconducting BCS-reduced Hubbard models to analyze the finite size behavior in small finite clusters. The ground state of the BCS-reduced Hubbard models is calculated with the stochastic diagonalization without any approximations. As result of these analyses we propose a new finite size scaling ansatz for the Hubbard model, which is able describe the finite size effects in a consistent way taking the corrections to scaling into account, which are dominant for weak interaction strength and small clusters. With this new finite size scaling ansatz it is possible to give evidence for superconductivity for all interaction strengths for both the attractive tt'-Hubbard model (with s-wave symmetry) and the repulsive tt'-Hubbard model (with d x 2 −y 2 -wave symmetry). Int. J. Mod. Phys. C 1998.09:943-985. Downloaded from www.worldscientific.com by FLINDERS UNIVERSITY LIBRARY on 02/03/15. For personal use only.

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“…The 2D version of the Hamiltonian (1) has been derived by Simon and Aligia as an effective one-band model resulting from tracing out the oxygen degrees of freedom in cuprates [3]. The model was studied by analytical and numerical methods, especially in the limit of strong interactions [28][29][30]21,[31][32][33][34][35][36]. The main attention was focused on the search for a superconducting ground state.…”

Section: Introductionmentioning

confidence: 99%

Weak-coupling phase diagram of the extended Hubbard model with correlated-hopping interaction

Japaridze

Kampf

1999

Phys. Rev. B

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A one-dimensional model of interacting electrons with on-site U , nearest-neighbor V , and correlatedhopping interaction T * is studied at half-filling using the continuum-limit field theory approach. The ground-state phase diagram is obtained for a wide range of coupling constants. In addition to the insulating spin-and charge-density wave phases for large U and V , respectively, we identify bond-located ordered phases corresponding to an enhanced Peierls instability in the system for T * > 0, |U − 2V | < 8T * /π and to a staggered magnetization located on bonds between sites for T * < 0, |U −2V | < 8|T * |/π. The general ground state phase diagram including insulating, metallic, and superconducting phases is discussed.

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Off-Diagonal Long-Range Order in Generalized Hubbard Models

Cited by 10 publications

References 26 publications

Superconductivity with s and p symmetries in an extended Hubbard model with correlated hopping

Superconductivity with s and p symmetries in an extended Hubbard model with correlated hopping

Finite Size Scaling in the tt'-Hubbard Model and in BCS-Reduced Hubbard Models

Weak-coupling phase diagram of the extended Hubbard model with correlated-hopping interaction

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