Theory of Spin Fluctuation-Induced Superconductivity Based on ad-pModel. II. –Superconducting State–

Takimoto, Tetsuya; Moriya, Tôru

doi:10.1143/jpsj.67.3570

Cited by 50 publications

(49 citation statements)

References 38 publications

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“…52) The resonance peak in the superconducting state is attributed to the anti-ferromagnetic correlation and the d-wave superconductivity. 46,53,54) Our result shows the sharp resonance peak in the superconducting state, which is caused by the same mechanism. Moreover, we investigate the behavior of the resonance peak in the pseudogap state.…”

Section: (B))supporting

confidence: 61%

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Theory on Superconducting Transition from Pseudogap State

2000

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The anomalous properties of High-T c cuprates are investigated both in the normal state and in the superconducting state. In particular, we pay attention to the pseudogap in the normal state and the phase transition from the pseudogap state to the superconducting state. The pseudogap phenomena observed in cuprates are naturally understood as a precursor of the strong coupling superconductivity. We have previously shown by using the self-consistent Tmatrix calculation that the pseudogap is a result of the strong superconducting fluctuations which are accompanied by the strong coupling superconductivity in quasi-two dimensional systems [J. Phys. Soc. Jpn. 68 (1999) 2999.]. We extend the scenario to the superconducting state. The close relation between the pseudogap state and the superconducting state is pointed out. Once the superconducting phase transition occurs, the superconducting order parameter rapidly grows rather than the result of BCS theory. With the rapid growth of the order parameter, the gap structure becomes sharp, while it is remarkably broad in the pseudogap state. The characteristic energy scale of the gap does not change. These results well explain the phase transition observed in the spectroscopic measurements. Further, we calculate the magnetic and transport properties which show the pseudogap phenomena. The comprehensive understanding of the NMR, the neutron scattering, the optical conductivity and the London penetration depth is obtained both in the pseudogap state and in the superconducting state. Many experiments such as the nuclear magnetic resonance (NMR), 1) optical conductivity, 2) transport, 3) electronic specific heat, 4) angle-resolved photo-emission spectroscopy (ARPES), 5) tunneling *

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Section: (B))supporting

confidence: 61%

“…For example, the rapid growth of the order parameter is also shown in the FLEX calculation. 46) We consider that the rapid growth obtained by the FLEX calculation is caused by the suppression of the de-pairing effect due to the low frequency spin fluctuations. This effect is different from that calculated in this paper.…”

Section: (B))mentioning

confidence: 99%

Theory on Superconducting Transition from Pseudogap State

2000

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“…13,14) The ratio 2∆ s /T c ∼ 12 has been obtained by the FLEX approximation in the optimally-doped region. 74) Here, ∆ s is the maximum value of the gap function in the ordered state. The larger ratio is expected in the under-doped region.…”

Section: Pseudogap In the Single Particle Propertiesmentioning

confidence: 99%

“…71) Moreover, the FLEX approximation is used to explain the anomalous properties resulting from the anti-ferromagnetic spin fluctuations, such as the Hall coefficient, 72, 73) the neutron resonance peak and the dip-hump structure in ARPES. 74) The self-energy given by the FLEX approximation Σ F (k, iω n ) is expressed by the one-loop diagram exchanging the normal vertex V n (q, iΩ n ) ( Fig. 1(a)).…”

Section: §1 Introductionmentioning

confidence: 99%

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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“…The superconducting transition temperature was determined as the highest temperature where the set of equations (7)-(19) has a non zero solution for the gap function. Near the critical temperature the algoritm becomes unstable because of the rapid growth of order parameter which was found also in the F LEX calculations in [24], caused by the depairing effect due to low frequency spin fluctuations. In our case we consider the effect of the superconducting fluctuations.…”

Section: Resultsmentioning

confidence: 57%

Transport properties calculation in the superconducting state for a quasi-two-dimensional system

Moca

Macocian

2001

Physica C: Superconductivity

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We performed a self-consistent calculation of the transport properties of a d-wave superconductor. We used for calculations the T-matrix approximation. The coresponding equations were evaluated numerically directly on the real frequecy axis. We studied the ab-plane charge dynamics in the coherent limit. For the c-axis charge dynamics, we considered both, the coherent and the incoherent limit. We also have calculated the penetration depth in this model.

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Theory of Spin Fluctuation-Induced Superconductivity Based on ad-pModel. II. –Superconducting State–

Cited by 50 publications

References 38 publications

Theory on Superconducting Transition from Pseudogap State

Theory on Superconducting Transition from Pseudogap State

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

Transport properties calculation in the superconducting state for a quasi-two-dimensional system

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Theory of Spin Fluctuation-Induced Superconductivity Based on ad-pModel. II. –Superconducting State–

Cited by 50 publications

References 38 publications

Theory on Superconducting Transition from Pseudogap State

Theory on Superconducting Transition from Pseudogap State

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

Transport properties calculation in the superconducting state for a quasi-two-dimensional system

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Product

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