Antiferromagnetic Spin Fluctuations and Superconductivity in Two-Dimensional Metals -A Possible Model for High<i>T</i><sub>c</sub>Oxides

Moriya, Tôru; Takahashi, Yoshihiro; Ueda, Kazuo

doi:10.1143/jpsj.59.2905

Cited by 625 publications

(361 citation statements)

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“…The antiferromagnetic spin fluctuations described by χ s (q, iΩ n ) play a dominant role in the FLEX approximation. The characteristic results of the nearly anti-ferromagnetic Fermi liquid theory 17,53,54,55,56,59,60,72,73,75) are qualitatively reproduced within the FLEX approximation. The superconducting critical temperature T c is determined as the temperature below which the linearized Dyson-Gor'kov equation has a non-trivial solution ( Fig.…”

Section: §1 Introductionmentioning

confidence: 76%

“…The other is that the high critical temperature T c is obtained by the pairing interaction mediated by the anti-ferromagnetic spin fluctuations. 53,54) The spin fluctuations also result from the strong electron-electron correlation. Thus, the both factors are derived from the electron-electron correlation and should be described in a unified way.…”

Section: §1 Introductionmentioning

confidence: 99%

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Pseudogap Phenomena and Superconducting Fluctuations in Hubbard Model for High-T_cCuprates

2001

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The pseudogap phenomena in High-Tc cuprates are investigated on the basis of the Hubbard model which includes only the on-site repulsive interaction U . We consider the pairing scenario for the pseudogap. The pseudogap arises from the resonance scattering due to the strong superconducting fluctuations. First, the electronic state and the anti-ferromagnetic spin fluctuations are calculated by using the fluctuation exchange (FLEX) approximation. The T-matrix which is the propagator of the superconducting fluctuations is calculated by extending theÉliashberg equation. The characteristics of the superconducting fluctuations due to the pairing interaction arising from the spin fluctuations are represented in the T-matrix. The self-energy due to the superconducting fluctuations is calculated by the T-matrix approximation. The pseudogap is shown in the single particle properties and the magnetic properties. Moreover, a comprehensive explanation of the doping dependence of the pseudogap is obtained. Furthermore, we apply the theory to the electron-doped cuprates and obtain the consistent results with the recent experiments. Finally, the self-consistent calculation for the spin fluctuations, superconducting fluctuations and the single particle properties are carried out within the FLEX and the self-consistent T-matrix approximations. The relation between the superconducting fluctuations and the spin fluctuations are clarified. The calculated superconducting critical temperature Tc is remarkably reduced from the results of the mean field (FLEX) calculation. In particular, it is shown that the critical temperature decreases with decreasing doping in the under-doped region with large U . The pseudogap phenomena in under-doped High-T c cuprates have been interested for many years. The pseudogap is considered to be a key issue for the comprehensive understanding of the High-T c superconductivity.The pseudogap phenomena mean the suppression of the spectral weight above T c without any long range order. They are universal phenomena observed in various compounds of High-T c cuprates in the under-doped region. First, the pseudogap was found in the magnetic excitation channel by the nuclear magnetic resonance (NMR) experiment. 1) At present, the pseudogap phenomena have been observed in various quantities which include NMR, 1, 2, 3, 4, 5, 6, 7) neutron scattering, 8) transport, 9, 10) optical spectrum, 11) electronic specific heat, 12) density of states 13) and the single particle spectral weight. 14) The experimental results are reviewed in ref. 15.There are many theoretical scenarios proposed for the pseudogap phenomena. An important one is the resonating valence bond (RVB) theory. The RVB theory is an approach from the non-Fermi liquid state and attributes the pseudogap to the singlet pairing of the spinons. 16) As an approach from the Fermi liquid state, the magnetic * E-mail: yanase@hosi.phys.s.u-tokyo.ac.jp * * Present address: Department of Physics, University of Tokyo, Tokyo 113-0033 scenario has been investigated. 17,18) ...

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Section: §1 Introductionmentioning

confidence: 76%

Section: §1 Introductionmentioning

confidence: 99%

Pseudogap Phenomena and Superconducting Fluctuations in Hubbard Model for High-T_cCuprates

2001

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“…The superconductivity in iron pnictides [1,2] and chalcogenides [3], with the interactions resulting from charge and spin degrees of freedom of electrons delicately balanced [4,5,6], provide a unique opportunity to unravel the mystery of unconventional superconductivity [7,8,9,10]. From the experimental characterizations [11] of the superconducting state of the iron pnictides and chalcogenides as well as theoretical calculations [12], it seems clear that the superconductivity in these alloys is not mediated by the phonons [13].…”

Section: Introductionmentioning

confidence: 99%

Effects of disorder in FeSe: anab initiostudy

Singh¹

2010

J. Phys.: Condens. Matter

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Abstract. Using the coherent-potential approximation, we have studied the effects of excess Fe, Se-deficiency, and substitutions of S, Te on Se sub-lattice and Co, Ni and Cu on Fe sub-lattice in FeSe. Our results show that (i) a small amount of excess Fe substantially disorders the Fe-derived bands while Se-deficiency affects mainly the Se-derived bands, (ii) the substitution of S or Te enhances the possibility of Fermi surface nesting, specially in FeSe 0.5 Te 0.5 , in spite of disordering the Se-derived bands, (iii) the electron doping through Co, Ni or Cu disorders the system and pushes down the Fe-derived bands, thereby destroying the possibility of Fermi surface nesting. A comparison of these results with the rigid-band, virtual-crystal and supercell approximations reveals the importance of describing disorder with the coherent-potential approximation.

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“…A persuasive scenario is that the superconductivity comes from a pairing interaction mediated by antiferromagnetic(AF) spin fluctuations. A phenomenological calculation [2][3][4][5] along this line has succeeded in reproducing anisotropic dwave superconductivity as well as anomalous normal-state properties. Analytic calculations on a microscopic level with the fluctuation exchange approximation (FLEX), developed by Bickers et al 6 , has also been applied to the Hubbard model on the two-dimensional(2D) square lattice 7,8 to show the occurrence of the superconductivity.…”

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confidence: 99%

“…4(b) for χ RPA (k, 0) shows that the width, a, of the χ RPA (k, 0) peak in each momentum direction is similar to those in 2D (Fig.1). Since the right-hand side of theÉliashberg equation (1) is normalized by N ∝ L D with L being the linear dimension of the system, λ ∝ (a/L) D is smaller in 3D than that in 2D when the main contribution of V (2) to λ is confined around (π, π) or (π, π, π). So we can conclude that this is the main reason why 2D differs from 3D.…”

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confidence: 99%

Spin-fluctuation exchange study of superconductivity in two- and three-dimensional single-band Hubbard models

1999

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Antiferromagnetic Spin Fluctuations and Superconductivity in Two-Dimensional Metals -A Possible Model for HighT_cOxides

Cited by 625 publications

References 22 publications

Pseudogap Phenomena and Superconducting Fluctuations in Hubbard Model for High-T_cCuprates

Pseudogap Phenomena and Superconducting Fluctuations in Hubbard Model for High-T_cCuprates

Effects of disorder in FeSe: anab initiostudy

Spin-fluctuation exchange study of superconductivity in two- and three-dimensional single-band Hubbard models

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Antiferromagnetic Spin Fluctuations and Superconductivity in Two-Dimensional Metals -A Possible Model for HighTcOxides

Cited by 625 publications

References 22 publications

Pseudogap Phenomena and Superconducting Fluctuations in Hubbard Model for High-TcCuprates

Pseudogap Phenomena and Superconducting Fluctuations in Hubbard Model for High-TcCuprates

Effects of disorder in FeSe: anab initiostudy

Spin-fluctuation exchange study of superconductivity in two- and three-dimensional single-band Hubbard models

Contact Info

Product

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Antiferromagnetic Spin Fluctuations and Superconductivity in Two-Dimensional Metals -A Possible Model for HighT_cOxides

Pseudogap Phenomena and Superconducting Fluctuations in Hubbard Model for High-T_cCuprates

Pseudogap Phenomena and Superconducting Fluctuations in Hubbard Model for High-T_cCuprates