Normal-state properties of BEDT-TTF compounds and the superconductivity pairing mechanism

Louati, R.; Charfi‐Kaddour, S.; Ali, Amir; Bennaceur, R.; Héritier, M.

doi:10.1103/physrevb.62.5957

Cited by 31 publications

(45 citation statements)

References 36 publications

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“…Thus, in organic superconductors, similar to cuprate superconductors, pressure has the effect of increasing the Q2D carrier density by transfering holes from other parts of the Fermi surface to those bands that support superconductivity [14]. Fig.…”

Section: The Pressure Medium Independent Correlation Between T C and mentioning

confidence: 99%

“…Louati et al [14] considered the ratio of the transfer integrals t b /t c to be the most critical parameter for κ-(BEDT-TTF) 2 X salts. This ratio of transfer integrals has been calculated for the Fluorinert and petroleum spirit measurements [15], and is plotted against T c in figure 4.…”

Section: The Pressure Medium Independent Correlation Between T C and mentioning

confidence: 99%

“…The increase of the Q2D carrier density can be understood as a charge carrier transfer from the Q1D sections of the Fermi surface to the Q2D hole pockets. Assuming that it is only the Q2D carriers that are superconducting [14], pressure applied to κ-(BEDT-TTF) 2 Cu(SCN) 2 can be understood to increase the carrier concentration of the superconducting carriers, similar to the pressure-induced carrier increase observed in cuprate superconductors.…”

Section: Introductionmentioning

confidence: 96%

“…A highly critical parameter for the material is the ratio of the interdimer transfer integrals t b /t c [14], which has been predicted [14] and observed [15] to increase under pressure. This pressure induced increase is currently considered to be the driving force of the different pressure-induced phase transitions observed in κ-(BEDT-TTF) 2 Cu(SCN) 2 [14]. Recent studies [13,15] have also discussed and investigated the importance of the out-of plane direction, the crystallographic a ′ -direction perpendicular to the bc-plane, for a more general understanding of the general physical properties of κ-(BEDT-TTF) 2 Cu(SCN) 2 .…”

Section: Introductionmentioning

confidence: 97%

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Comparative magnetotransport andT_cmeasurements on -(BEDT-TTF)₂Cu(SCN)₂under pressure

Klehe¹,

Biggs²,

Kuntscher³

et al. 2004

J. Phys.: Condens. Matter

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Abstract.We compare magnetotransport measurements under pressure on the organic superconductor κ-(BEDT-TTF) 2 Cu(SCN) 2 with different pressure-media and discover that the results are pressure media dependent. This pressure-medium dependence is thought to originate from the difference in thermal contraction between the very soft and highly anisotropic sample and the isotropically contracting, but solid pressure medium, thus resulting in non-hydrostatic pressure on the sample. However, comparison of pressure measurements with different media reveals a pressure-medium independent correlation between the superconducting transition temperature, Tc, and the size of the quasi 2-dimensional Fermi surface pocket and thus the quasi 2-dimensional carrier density in κ-(BEDT-TTF) 2 Cu(SCN) 2 . The observed pressure-induced increase in the quasi 2-dimensional carrier density can be interpreted as a transfer of carriers from quasi 1-dimensional Fermi surface sections, reminiscent of a mechanism in cuprate superconductors, where pressure is known to transfer carriers from the insulating charge reservoir layers into the conducting cuprate sheets.

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Section: The Pressure Medium Independent Correlation Between T C and mentioning

confidence: 99%

Section: The Pressure Medium Independent Correlation Between T C and mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 97%

See 2 more Smart Citations

Comparative magnetotransport andT_cmeasurements on -(BEDT-TTF)₂Cu(SCN)₂under pressure

Klehe¹,

Biggs²,

Kuntscher³

et al. 2004

J. Phys.: Condens. Matter

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“…The system will be instability to an AF Néel state if the bare U is used, which is not consistent with the metallic normal state considered here. This is due to the artifact of the RPA approximation, which overestimate the AF correlation as was found in the cases of the cuprate system [18] and also organic materials [19]. Considering the conclusion of Bulut et al [17] and that the instability to an AF Néel state occurs when U ≥ 3.4t , we chooseŪ = 3t here.…”

mentioning

confidence: 99%

Test for Pairing Symmetry Based on Spin Fluctuations in the Organic Superconductorκ−(BEDT−T
Li
¹

2003
Phys. Rev. Lett.
17
0
0
0
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We propose that the superconducting pairing symmetry of organic superconductors κ-(BEDT-TTF)2X can be determined by measuring the position in momentum space of the incommensurate peaks of the spin susceptibility. We show that the positions of these peaks are uniquely determined by the symmetry of the superconducting state and the geometry of Fermi surface. Based on the effective Hubbard model on an anisotropic triangular lattice, we demonstrate the different incommensurate patters of spin responses for d x 2 −y 2 -and dxy-like pairing states. In addition, we predict the nonexistence of the spin resonance mode in this compound, which is an important feature in high-Tc superconductors.PACS number: 74.70. Kn,74.20.Rp Layered organic superconductors based on the (BEDT-TTF) molecule are rich examples of strongly correlated electron systems in low dimensions [1]. Among them, κ-(BEDT-TTF) 2 X(κ-(ET)) has attracted considerable attention, because they share many similarities to cuprate superconductors [2], such as the proximity of its superconducting(SC) phase with the antiferromagnetic(AF) insulating phase which suggests that it may be an unconventional superconductor. Understanding its SC mechanism could therefore provide important insight into the origin of the unconventional superconductivity. As an essential step for this process, intensive experimental and theoretical investigations have been carried out to identify its SC pairing symmetry, but no consensus has been achieved yet [3]. The NMR [4] and millimeterwave transmission experiment [5] suggests d x 2 −y 2 symmetry (A different interpretation has been proposed for the latter result [6]). However, the recent thermal conductivity [7] and scan tunneling spectroscopy measurements [8] predict that it is more like d xy than d x 2 −y 2 . Moreover, a nodeless s-wave SC state is also suggested in recent specific-heat measurements [9]. Theoretically, the d x 2 −y 2 -like pairing symmetry is favored in the model in which the superconductivity is mediated by strong AF fluctuations [10,11] and also in a model of small-q phonon mediated superconductivity [12]. However, it is shown that the d xy -like superconductivity is also likely and can dominate over d x 2 −y 2 wave, when a more realistic model is considered [13].In this letter, we propose an orientational-dependent method aiming at a direct determination of the gap anisotropy in κ-(ET). It is to measure the q-space position of the incommensurate(IC) peaks of the dynamical spin susceptibility by inelastic neutron scatterings. Our proposal is based on: i) it is believed that AF spin fluctuations are strong in this material [1,2,4]; ii) the central issue at problem about the gap symmetry is what the direction of the gap nodes is or if there are gap nodes. The underlying physics is that the particle-hole excitations, which contribute to the spin susceptibility, are only available for the node-to-node transitions in the SC state, if the excitation energy is lower than 2∆ 0 (∆ 0 the magnitude of the SC gap). Therefore, t...

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Normal state properties of BEDT compounds

Joo

Meddeb

Charfi‐Kaddour

et al. 2004

Physica Status Solidi (b)

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PACS 74.20.Mn, 74.25Fy, 74.70.Kn The κ-(BEDT-TTF) 2 X organic superconductors are described by a two parameter 2D surface model, in which bandwidth and departure from perfect nesting can be varied. We have studied the spin fluctuation effect on the normal state properties in a Fermi liquid approach using the RPA approximation. The calculated NMR relaxation rate exhibits a peak in 1/(T 1 T), which strongly decreases when the departure from the perfect nesting of the Fermi surface and the bandwidth decrease. Our calculations show also that the spin fluctuations induce an unusual resistivity temperature dependence. These results are in a good agreement with experimental data done in κ-(BEDT-TTF) 2 X, at least qualitatively.

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Normal-state properties of BEDT-TTF compounds and the superconductivity pairing mechanism

Cited by 31 publications

References 36 publications

Comparative magnetotransport andT_cmeasurements on -(BEDT-TTF)₂Cu(SCN)₂under pressure

Comparative magnetotransport andT_cmeasurements on -(BEDT-TTF)₂Cu(SCN)₂under pressure

Test for Pairing Symmetry Based on Spin Fluctuations in the Organic Superconductorκ−(BEDT−T
Li
¹

2003
Phys. Rev. Lett.
17
0
0
0
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Normal state properties of BEDT compounds

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Normal-state properties of BEDT-TTF compounds and the superconductivity pairing mechanism

Cited by 31 publications

References 36 publications

Comparative magnetotransport andTcmeasurements on -(BEDT-TTF)2Cu(SCN)2under pressure

Comparative magnetotransport andTcmeasurements on -(BEDT-TTF)2Cu(SCN)2under pressure

Test for Pairing Symmetry Based on Spin Fluctuations in the Organic Superconductorκ−(BEDT−TLi1 2003Phys. Rev. Lett.17000View full textAdd to dashboardCite

Normal state properties of BEDT compounds

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Comparative magnetotransport andT_cmeasurements on -(BEDT-TTF)₂Cu(SCN)₂under pressure

Comparative magnetotransport andT_cmeasurements on -(BEDT-TTF)₂Cu(SCN)₂under pressure

Test for Pairing Symmetry Based on Spin Fluctuations in the Organic Superconductorκ−(BEDT−T
Li
¹

2003
Phys. Rev. Lett.
17
0
0
0
View full text Add to dashboard Cite