Superconductivity in narrow-band systems with local nonretarded attractive interactions

Micnas, R.; Ranninger, J.; Robaszkiewicz, S.

doi:10.1103/revmodphys.62.113

Cited by 1,663 publications

(1,523 citation statements)

References 342 publications

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“…If we let the coupling Í assume negative values, one has the attractive Hubbard model. Physically, this local attraction can have its origin in the coupling of fermions to extended (through polaron formation) or local phonons (such as vibrational modes of chemical complexes) [3]. Given that its weak coupling limit describes the usual BCS theory, and that the real-space pairing is more amenable to numerical calculations, this model has also been useful in elucidating several properties of both conventional and hightemperature superconductors [3].…”

Section: Introduction To Quantum Monte Carlo Simulations1 Introductionmentioning

confidence: 99%

Introduction to quantum Monte Carlo simulations for fermionic systems

Santos¹

2003

Braz. J. Phys.

151

137

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We tutorially review the determinantal Quantum Monte Carlo method for fermionic systems, using the Hubbard model as a case study. Starting with the basic ingredients of Monte Carlo simulations for classical systems, we introduce aspects such as importance sampling, sources of errors, and finite-size scaling analyses. We then set up the preliminary steps to prepare for the simulations, showing that they are actually carried out by sampling discrete Hubbard-Stratonovich auxiliary fields. In this process the Green's function emerges as a fundamental tool, since it is used in the updating process, and, at the same time, it is directly related to the quantities probing magnetic, charge, metallic, and superconducting behaviours. We also discuss the as yet unresolved 'minus-sign problem', and two ways to stabilize the algorithm at low temperatures.

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Section: Introduction To Quantum Monte Carlo Simulations1 Introductionmentioning

confidence: 99%

Introduction to quantum Monte Carlo simulations for fermionic systems

Santos¹

2003

Braz. J. Phys.

151

137

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“…Refs. [12][13][14][15][16]). In particular the exchange-hopping interaction is the driving force towards the d-wave superconductivity [15] and p-wave superconductivity [16].…”

Section: Introductionmentioning

confidence: 99%

Magnetic ordering of itinerant systems: the role of kinetic interactions

Górski

Mizia

2004

Physica B: Condensed Matter

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The possibility of ferromagnetic ordering is revisited in the band model. The coherent potential approximation decoupling has been used for the strong on-site Coulomb interaction. The driving forces towards the ferromagnetism are the on-site and inter-site molecular fields coming from different Coulomb interactions. Another driving force is the lowering of the kinetic energy with growing magnetic moment coming from the dependence of the hopping integrals on occupation of the neighboring sites involved in hopping. This effect is described by the hopping interaction, ∆t , and by what we call the exchange-hopping interaction, tex. The exchange-hopping interaction, which is the difference in hopping integrals for different occupation of neighboring lattice sites, acts in analogous way to the Hund's magnetic exchange interaction. The results are calculated for semi-elliptic density of states (DOS) and for the distorted semi-elliptic DOS with the maximum around the Fermi energy. They show a natural tendency towards the magnetic ordering at the end of the 3d row for the DOS with maximum density around the Fermi energy, when the hopping integrals grow with the occupation of the neighboring lattice sites.

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“…(8,9) and (11,12), respectively. The theoretical prediction for the superconducting gap in the single-particle spectrum ∆ 0 compared to the experimental data for the "coherence energy" ∆ c (filled symbols) and the "pseudogap" energy ∆ p (open symbols) from ref.…”

Section: Resultsmentioning

confidence: 99%

“…The four parameters of the delta-shell model are the "coupling constant" g (which has dimensions of energy × length), the distance at which the attraction takes place r 0 , the effective mass m * , and the density of charge carriers, per unit volume, n. Although formally similar to the "contact potential" of BCS theory, the physics described by the delta-shell potential are very different: it corresponds to non-retarded attraction at a finite distance r 0 . In that sense, it is more similar to the Hubbard-like models with nearest-neighbour attraction [9]. But note that in the delta-shell model the distance r 0 at which the electrons attract each other is a free parameter that can be varied continuously, and the noninteracting dispersion relation is that of free electrons with an effective mass m * .…”

Section: The Modelmentioning

confidence: 96%

On the nature of the superconducting gap in the cuprates

Quintanilla¹,

Györffy²

2002

J. Phys.: Condens. Matter

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Recent experiments indicate that the excitation spectrum of the cuprates is characterised, in the superconducting state, by two energy scales: the "coherence energy" ∆ c and the "pseudogap" ∆ p . Here we consider a simple generalisation of the BCS model that yields exotic pairing and can describe, phenomenologically, the generic trends in the critical temperature T c of cuprate superconductors. We use the model to predict the gap in the single-particle spectrum arising from the superconductivity and we find evidence that it corresponds to the lower of the two energy scales, ∆ c , seen in the experiments. This provides further support to the view that the origin of the pseudogap is not superconducting fluctuations.

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Superconductivity in narrow-band systems with local nonretarded attractive interactions

Cited by 1,663 publications

References 342 publications

Introduction to quantum Monte Carlo simulations for fermionic systems

Introduction to quantum Monte Carlo simulations for fermionic systems

Magnetic ordering of itinerant systems: the role of kinetic interactions

On the nature of the superconducting gap in the cuprates

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