Hall effect and resistivity in high-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi>T</mml:mi></mml:mrow><mml:mrow><mml:mi>c</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math>superconductors: The conserving approximation

Kontani, Hiroshi; Kanki, Kazuki; Ueda, Ken–ichi

doi:10.1103/physrevb.59.14723

Cited by 219 publications

(435 citation statements)

References 70 publications

(144 reference statements)

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“…On the other hand, it has been known that electron correlation effects can in general affect the transport properties. 4,18 Specifically for the present material, a weak ferromagnetism has in fact been experimentally suggested in the τ -type organic conductors of the OOSS molecule. [19][20][21] A theoretical work on the single-band Hubbard model of this material has shown that ferromagnetism can appear originating from a flat-bottomed band dispersion and a dilute band filling.…”

Section: Discussionsupporting

confidence: 50%

Molecular Dependence of the Large Seebeck Effect in τ-Type Organic Conductors

et al. 2014

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We study the Seebeck effect in the τ -type organic conductors, τ -(EDO-S,S -DMEDT-TTF)2(AuBr2)1+y and τ -(P-S,S -DMEDT-TTF)2(AuBr2)1+y, where EDO-S,S -DMEDT-TTF and P-S,S -DMEDT-TTF are abbreviated as OOSS and NNSS, respectively, both experimentally and theoretically. Theoretically in particular, we perform first-principles band calculation for the two materials and construct a two-orbital model, on the basis of which we calculate the Seebeck coefficient. We show that the calculated temperature dependence of the Seebeck coefficient S is semi-quantitatively consistent with the experimental observation. In both materials, the absolute value of the Seebeck coefficient is maximum at a certain temperature, and this temperature is lower for NNSS than for OOSS. From a band structure viewpoint, we find that this can be traced back to the narrowness of the band gap between the upper and the lower pudding-mold type bands. On the other hand, the Seebeck coefficient of NNSS in the low temperature regime steeply increases with increasing temperature, which is due to the narrowness of the upper band. These differences in thermoelectric properties demonstrate the effectiveness of controlling the band structure through molecular modification.

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Section: Discussionsupporting

confidence: 50%

Molecular Dependence of the Large Seebeck Effect in τ-Type Organic Conductors

et al. 2014

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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: 61%

“…The anomalous properties of the Hall coefficient are well explained for not only hole-but also electron-doped cuprates on the basis of the same formalism treating the spin fluctuations. 72,73) Therefore, it is natural to expect the same mechanism for the superconductivity arising from the spin fluctuations. Actually, the instability of the d-wave superconductivity mediated by the spin fluctuations has been reported theoretically.…”

Section: Electron-doped Cupratesmentioning

confidence: 99%

“…Actually, the instability of the d-wave superconductivity mediated by the spin fluctuations has been reported theoretically. 72,101,102) We consider that the application to the electron-doped cuprates is an important test of the theories on High-T c cuprates. Here, it is shown that our theory properly describes the important properties of the electron-doped cuprates.…”

Section: Electron-doped Cupratesmentioning

confidence: 99%

“…The transformation of the Fermi surface is a characteristic feature of the nearly anti-ferromagnetic systems 56) and is confirmed by the FLEX approximation. 72) The effective Fermi energy for the superconducting fluctuations are renormalized by the above features.…”

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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Spin States and Transport in Correlated Electron Systems

Aoki

1999

Low-Dimensional Systems

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Hall effect and resistivity in high-Tcsuperconductors: The conserving approximation

Cited by 219 publications

References 70 publications

Molecular Dependence of the Large Seebeck Effect in τ-Type Organic Conductors

Molecular Dependence of the Large Seebeck Effect in τ-Type Organic Conductors

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

Spin States and Transport in Correlated Electron Systems

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Hall effect and resistivity in high-Tcsuperconductors: The conserving approximation

Cited by 219 publications

References 70 publications

Molecular Dependence of the Large Seebeck Effect in τ-Type Organic Conductors

Molecular Dependence of the Large Seebeck Effect in τ-Type Organic Conductors

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

Spin States and Transport in Correlated Electron Systems

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Product

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