D-wave Superconductivity in κ-(BEDT-TTF))2Cu(NCS)2

Maki, Kazumi; Puchkaryov, E.; Won, Hyung Jin

doi:10.1016/s0379-6779(98)00351-8

Cited by 20 publications

(16 citation statements)

References 25 publications

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“…Whilst nuclear magnetic resonance [5], penetration-depth [2], tunnelling [4] and other experiments [1] appear to suggest that the superconductivity in these salts may be d-wave-like and mediated by spin-density-wave-like fluctuations, some doubts have been cast by recent controversial specific heat measurements, which may suggest that the order parameter does not possess the required nodes [3]. Several theories [6,7,8,9] stress the importance of the details of the Fermi-surface topology in providing suitable prerequisites for superconductivity; if the Fermi-surface geometry and interactions are altered slightly, it appears that BCS-like s-wave superconductivity may be the dominant low-temperature groundstate [1].…”

Section: Introductionmentioning

confidence: 99%

Superconducting properties and Fermi-surface topology of the quasi-two-dimensional organic superconductor λ-(BETS)₂GaCl₄(BETS≡bis(ethylene-dithio)tetraselenafulvalene)

Mielke

Singleton

Nam

et al. 2001

J. Phys.: Condens. Matter

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Abstract. The Fermi surface topology of the organic superconductor λ-(BETS) 2 GaCl 4 has been determined using the Shubnikov-de Haas and magnetic breakdown effects and angle-dependent magnetoresistance oscillations. The former experiments were carried out in pulsed fields of up to 60 T, whereas the latter employed quasistatic fields of up to 30 T. All of these data show that the Fermi-surface topology of λ-(BETS) 2 GaCl 4 is very similar to that of the most heavily-studied organic superconductor, κ-(BEDT-TTF) 2 Cu(NCS) 2 , except in one important respect; the interplane transfer integral in λ-(BETS) 2 GaCl 4 is a factor ∼ 5 larger than that in κ-(BEDT-TTF) 2 Cu(NCS) 2 . The increased three-dimensionality of λ-(BETS) 2 GaCl 4 is manifested in radiofrequency penetration-depth measurements, which show a clear dimensional crossover in the behaviour of H c2 (T ). The radiofrequency measurements have also been used to extract the Labusch parameter determining the fluxoid interactions as a function of temperature, and to map the flux-lattice melting curve.

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Section: Introductionmentioning

confidence: 99%

Superconducting properties and Fermi-surface topology of the quasi-two-dimensional organic superconductor λ-(BETS)₂GaCl₄(BETS≡bis(ethylene-dithio)tetraselenafulvalene)

Mielke

Singleton

Nam

et al. 2001

J. Phys.: Condens. Matter

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“…The cryostat was placed in 31 and 33 T Bitter coils at NHMFL, Tallahassee. This broadened transition region appears to be an intrinsic feature of (BEDT-TTF)-based superconductors 18 ; it has been attributed to dissipation due to superconducting weak links in inhomogeneous samples 19,20 , magnetoresistance due to a lattice distortion via coupling with the quantised vortices 21 and dissipation caused by fluctuations characteristic of a d-wave superconductor 22 . All of the models mentioned regard the broadened transition region as an artefact of the superconducting state; in common with others 13,18 , we therefore choose a field B p at which the extrapolations of the normal-state magnetoresistance and the transition region intercept (Fig.…”

mentioning

confidence: 99%

Observation of the Fulde-Ferrell-Larkin-Ovchinnikov state in κ-(BEDT-TTF)2Cu(NCS)2

Symington¹,

Singleton²,

Nam³

et al. 2001

Synthetic Metals

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“…The combination of unconventional superconductivity and a tractable analytical representation of the band structure makes the k-͑BEDT-TTF͒ 2 X superconductors attractive for theoretical studies, and a number of authors [9,10,12,13] have explored the possibility of d-wave superconductivity mediated by spin fluctuations. Such approaches predict that the superconducting order parameter will have four, roughly perpendicular, gap nodes, the exact orientation of the nodes depending on the underlying details of the Fermi surface [10,12].…”

mentioning

confidence: 99%

Millimeter-Wave Magneto-optical Determination of the Anisotropy of the Superconducting Order Parameter in the Molecular Superconductorκ-(BEDT−TTF)2
Schrama
¹
,
Rzepniewski
²
,
Edwards
³

et al. 1999
Phys. Rev. Lett.
60
3
45
2
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We have used a millimeter-wave magneto-optical technique to study the angle dependence of the high-frequency conductivity of the molecular superconductor k-͑BEDT-TTF͒ 2 Cu͑NCS͒ 2 . The data strongly suggest that the superconducting gap has nodes directed along the b and c directions of the crystal, in agreement with recent theoretical predictions. This supports the idea that the superconductivity in k-͑BEDT-TTF͒ 2 Cu͑NCS͒ 2 is d wave in nature, and is mediated by spin fluctuations. PACS numbers: 74.25.Gz, 74.20.Mn, 74.25.Nf, 74.70.Kn The family of superconducting charge-transfer salts k-͑BEDT-TTF͒ 2 X, where X can, for example, be Cu͑NCS͒ 2 , Cu͓N͑CN͒ 2 ͔Br, or I 3 , has attracted considerable recent attention. A variety of experiments have suggested that the superconducting gap function may contain nodes at certain points on the Fermi surface; e.g., the 13 C NMR spin-lattice relaxation rate [1] varies as T 3 and the thermal conductivity [2] is proportional to T below the superconducting critical temperature T c . In addition, microwave penetration-depth studies [3] show a non-BCS-like behavior of the penetration depth as a function of T and the electronic component of the specific heat [4] has an unconventional field dependence below T c . However, Shubnikov-de Haas [5,6], magnetic breakdown [7], and angle-dependent magnetoresistance oscillation [8] experiments demonstrate that these salts have well-defined quasi-two-dimensional (Q2D) Fermi surfaces, indicating that the quasiparticles can be described by Fermi-liquid theory at low temperatures (the Fermi surface is shown schematically as an inset of Fig. 1). Furthermore, it has been possible to fit experimental Fermi-surface-topology data to a simplified model of the tight-binding band structure (the so-called effective dimer model) to a good degree of accuracy [5,[9][10][11].The combination of unconventional superconductivity and a tractable analytical representation of the band structure makes the k-͑BEDT-TTF͒ 2 X superconductors attractive for theoretical studies, and a number of authors [9,10,12,13] have explored the possibility of d-wave superconductivity mediated by spin fluctuations. Such approaches predict that the superconducting order parameter will have four, roughly perpendicular, gap nodes, the exact orientation of the nodes depending on the underlying details of the Fermi surface [10,12]. Experiments performed thus far have merely detected the probable presence of the gap nodes, without giving information about their relative orientation. In this paper, we use a millimeter-wave magneto-optical technique to determine the orientation of the gap nodes in k-͑BEDT-TTF͒ 2 Cu͑NCS͒ 2 . The data appear to be in good qualitative agreement with the predictions of Schmalian [10].The experiments were carried out on a number of crystals of k-͑BEDT-TTF͒ 2 Cu͑NCS͒ 2 , grown by FIG.

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D-wave Superconductivity in κ-(BEDT-TTF))2Cu(NCS)2

Cited by 20 publications

References 25 publications

Superconducting properties and Fermi-surface topology of the quasi-two-dimensional organic superconductor λ-(BETS)₂GaCl₄(BETS≡bis(ethylene-dithio)tetraselenafulvalene)

Superconducting properties and Fermi-surface topology of the quasi-two-dimensional organic superconductor λ-(BETS)₂GaCl₄(BETS≡bis(ethylene-dithio)tetraselenafulvalene)

Observation of the Fulde-Ferrell-Larkin-Ovchinnikov state in κ-(BEDT-TTF)2Cu(NCS)2

Millimeter-Wave Magneto-optical Determination of the Anisotropy of the Superconducting Order Parameter in the Molecular Superconductorκ-(BEDT−TTF)2
Schrama
¹
,
Rzepniewski
²
,
Edwards
³

et al. 1999
Phys. Rev. Lett.
60
3
45
2
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D-wave Superconductivity in κ-(BEDT-TTF))2Cu(NCS)2

Cited by 20 publications

References 25 publications

Superconducting properties and Fermi-surface topology of the quasi-two-dimensional organic superconductor λ-(BETS)2GaCl4(BETS≡bis(ethylene-dithio)tetraselenafulvalene)

Superconducting properties and Fermi-surface topology of the quasi-two-dimensional organic superconductor λ-(BETS)2GaCl4(BETS≡bis(ethylene-dithio)tetraselenafulvalene)

Observation of the Fulde-Ferrell-Larkin-Ovchinnikov state in κ-(BEDT-TTF)2Cu(NCS)2

Millimeter-Wave Magneto-optical Determination of the Anisotropy of the Superconducting Order Parameter in the Molecular Superconductorκ-(BEDT−TTF)2Schrama1, Rzepniewski2, Edwards3 et al. 1999Phys. Rev. Lett.603452View full textAdd to dashboardCite

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Superconducting properties and Fermi-surface topology of the quasi-two-dimensional organic superconductor λ-(BETS)₂GaCl₄(BETS≡bis(ethylene-dithio)tetraselenafulvalene)

Superconducting properties and Fermi-surface topology of the quasi-two-dimensional organic superconductor λ-(BETS)₂GaCl₄(BETS≡bis(ethylene-dithio)tetraselenafulvalene)

Millimeter-Wave Magneto-optical Determination of the Anisotropy of the Superconducting Order Parameter in the Molecular Superconductorκ-(BEDT−TTF)2
Schrama
¹
,
Rzepniewski
²
,
Edwards
³

et al. 1999
Phys. Rev. Lett.
60
3
45
2
View full text Add to dashboard Cite