Strong correlations versus<i>U</i>-center pairing and fractional Aharonov-Bohm effect

Kusmartsev, F. V.; Weisz, J. F.; Kishore, R.; Takahashi, Minoru

doi:10.1103/physrevb.49.16234

Cited by 41 publications

(34 citation statements)

References 55 publications

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“…In this caseE(Φ ↑ + 2π/N, Φ ↓ + 2π/N) = E(Φ ↑ , Φ ↓ ),since the shift in Φ σ can be absorbed decreasing one of the ν by 1, what is always possible if 0 = N ↓ = N f . For Φ ↑ = Φ ↓ , this result has been obtained previously[24]. Similarly, for the more interesting case with N d = 0, a change in both Φ σ by 2π/|N b − N e | can be counterbalanced by a change in the {ν ′ }, leading to…”

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confidence: 78%

Anomalous Flux Quantization in a Hubbard Ring with Correlated Hopping

1996

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We solve exactly a generalized Hubbard ring with twisted boundary conditions. The magnitude of the nearest-neighbor hopping depends on the occupations of the sites involved and the term which modifies the number of doubly occupied sites t AB 0. Although h-pairing states with offdiagonal long-range order are part of the degenerate ground state, the behavior of the energy as a function of the twist rules out superconductivity in this limit. A small t AB breaks the degeneracy and for moderate repulsive U introduce superconducting correlations which lead to "anomalous" flux quantization. [S0031-9007(96)00300-6] PACS numbers: 74.20.Mn, 71.27.+a, 71.30.+h, 71.28.+d One of the most interesting problems of the physics of highly correlated electronic systems is the characterization of the metallic, insulating, and superconducting phases, as well as the transitions among them. Kohn has shown that the Drude weight D c is the adequate quantity to identify the metal-insulator transition (MIT) [1], while Yang introduced the concept of off-diagonal long-range order (ODLRO) to characterize the superconducting nature of a metallic phase [2]. ODLRO in all relevant low-energy eigenstates implies a periodicity of h͞2e in the free energy as a function of a magnetic flux threading a system with annular topology. This "anomalous" flux quantization (AFQ) [3,4] in the ground state (GS) means E͑F 1 p͒ E͑F͒, where E is the GS energy and F is the twist angle. It is a necessary but not sufficient condition for superconductivity. Since D c ϳ ≠ 2 E͞≠F 2 , the function E͑F͒ gives crucial information about the metallic and superconducting character of the system [1,4,5].Exactly solvable highly correlated models displaying a MIT or ODLRO are good laboratories to investigate the nature of the MIT and electronic mechanisms of superconductivity. The Bethe ansatz solution with twisted boundary conditions of the one-dimensional (1D) Hubbard model [6] allowed application of Kohn's ideas to the MIT in this model [6,7]. In addition, the interest in electronic models exhibiting superconductivity (or dominant superconducting correlations at long distances in 1D), in particular, those with correlated hopping increases recently [8][9][10][11][12]. However, very few exact results exist. Several of them are related with the so-called h-pairing mechanism, which allows us to construct eigenstates with ODLRO [8][9][10][11]. In particular, the widely studied [13][14][15] effective model for cuprate superconductors, H H U 1 H t U X i n i" n i# 1 X ͗ij͘s ͑c y is c js 1 H.c.͒3 ͕t AA ͑1 2 n is ͒ ͑1 2 n js ͒ 1 t BB n is n js 1 t AB ͓n is ͑1 2 n js ͒ 1 n js ͑1 2 n is ͔͖͒ ,has been exactly solved recently in 1D in the limit t AB 0 for open [9] and periodic [10,11] boundary conditions. hpairing states with ODLRO are part of the degenerate GS for moderate on-site repulsion U and arbitrary band filling. Unfortunately, the function E͑F͒ has not been obtained and, then, the AFQ and D c were not studied. Our main interest in this study is motivated by the following two fact...

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confidence: 78%

Anomalous Flux Quantization in a Hubbard Ring with Correlated Hopping

1996

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“…Similar equations to Eqs. (21)- (24) have been derived for the ground state, in the study of persistent currents in finite-size rings 34 . If we use Eqs.…”

Section: A Bethe-ansatz Equationsmentioning

confidence: 99%

Finite-temperature transport in finite-size Hubbard rings in the strong-coupling limit

Peres¹,

Dias²,

Sacramento³

et al. 2000

Phys. Rev. B

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We study the current, the curvature of levels, and the finite temperature charge stiffness, D(T, L), in the strongly correlated limit, U ≫ t, for Hubbard rings of L sites, with U the on-site Coulomb repulsion and t the hopping integral. Our study is done for finite-size systems and any band filling. Up to order t we derive our results following two independent approaches, namely, using the solution provided by the Bethe ansatz and the solution provided by an algebraic method, where the electronic operators are represented in a slave-fermion picture. We find that, in the U = ∞ case, the finitetemperature charge stiffness is finite for electronic densities, n, smaller than one. These results are essencially those of spinless fermions in a lattice of size L, apart from small corrections coming from a statistical flux, due to the spin degrees of freedom. Up to order t, the Mott-Hubbard gap is ∆MH = U − 4t, and we find that D(T ) is finite for n < 1, but is zero at half-filling. This result comes from the effective flux felt by the holon excitations, which, due to the presence of doubly occupied sites, is renormalized to, and which is zero at half-filling, with N d and N h being the number of doubly occupied and empty lattice sites, respectively. Further, for half-filling, the current transported by any eigenstate of the system is zero and, therefore, D(T ) is also zero.

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“…The parity effect is not destroyed by spin, finite temperature or disorder [5,7]. Interactions do not destroy the parity effect but interactions with spin can lead to the creation of a fractional Aharonov-Bohm effect, which has however not been observed experimentally yet [8][9][10][11][12][13][14][15][16]. The parity effect is also observed in multichannel simulations [17].…”

Section: Introductionmentioning

confidence: 99%

Nature of eigenstates in a mesoscopic ring coupled to a side branch

Sreeram¹,

Deo²

1996

Physica B: Condensed Matter

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We formalize the parity effect of a multichannel ring coupled to a side branch using the tight binding model. We find that the tight binding model gives slightly different result from the continuum model. We also show that some states of the system can be nonmagnetic. In the multichannel ring coupled to a side branch, the persistent current in the ring does not change sign, over gigantic fluctuations in N (the number of particles in the ring).

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Strong correlations versusU-center pairing and fractional Aharonov-Bohm effect

Cited by 41 publications

References 55 publications

Anomalous Flux Quantization in a Hubbard Ring with Correlated Hopping

Anomalous Flux Quantization in a Hubbard Ring with Correlated Hopping

Finite-temperature transport in finite-size Hubbard rings in the strong-coupling limit

Nature of eigenstates in a mesoscopic ring coupled to a side branch

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