Determination of a mass isotope effect on Tc in an electron-donor-based organic superconductor, κ-(ET)2Cu(NCS)2, where ET represents bis(ethylenedithio)tetrathiafulvalene

Kini, A. M.; Carlson, K. Douglas; Wang, Hsien‐Hau; Schlueter, J. A.; Dudek, James D.; Sirchio, Scott A.; Geiser, U.; Lykke, Keith R.; Williams, Jack M.

doi:10.1016/0921-4534(96)00237-7

Cited by 50 publications

(47 citation statements)

References 28 publications

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“…Recent studies have shown the importance of electron-phonon interaction for the pairing mechanism. 48,49,50,51,52,53 For example, isotope effect studies of the superconducting T c by isotope substitution of C and S atoms on the ET-molecules have singled out the effect of intramolecular vibrations for the superconducting pairing 48,49 A shift of phonon frequency caused by the superconducting transition has also been observed with inelastic neutron scattering. 50 This shift indicates that the coupling to intermolecular acoustic phonons contributes to superconductivity.…”

Section: Layered Organic Superconductorsmentioning

confidence: 99%

Electronic collective modes and superconductivity in layered conductors

2003

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A distinctive feature of layered conductors is the presence of low-energy electronic collective modes of the conduction electrons. This affects the dynamic screening properties of the Coulomb interaction in a layered material. We study the consequences of the existence of these collective modes for superconductivity. General equations for the superconducting order parameter are derived within the strong-coupling phonon-plasmon scheme that account for the screened Coulomb interaction. Specifically, we calculate the superconducting critical temperature Tc taking into account the full temperature, frequency and wave-vector dependence of the dielectric function. We show that low-energy plasmons may contribute constructively to superconductivity. Three classes of layered superconductors are discussed within our model: metal-intercalated halide nitrides, layered organic materials and high-Tc oxides. In particular, we demonstrate that the plasmon contribution (electronic mechanism) is dominant in the first class of layered materials. The theory shows that the description of so-called "quasi-two-dimensional superconductors" cannot be reduced to a purely 2D model, as commonly assumed. While the transport properties are strongly anisotropic, it remains essential to take into account the screened interlayer Coulomb interaction to describe the superconducting state of layered materials.

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Section: Layered Organic Superconductorsmentioning

confidence: 99%

Electronic collective modes and superconductivity in layered conductors

2003

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“…448 However, the inverse isotope effect for -(ET) 2 I 3 is not convincing since its T c is so sensitive to the external and internal circumstances as described in section 3.5. . 480,481,[522][523][524][525][526] Since the superconductivity of -(ET) 2 -Cu[N(CN) 2 ]Cl appears only under pressure, no proper discussion concerning the isotope effect is possible unless the uniaxial stress method is applied on the salt (see next section). These above results were obtained by resistivity measurements.…”

Section: Inverse Isotope Effect; Currentlymentioning

confidence: 99%

Development of Conductive Organic Molecular Assemblies: Organic Metals, Superconductors, and Exotic Functional Materials

Saito¹,

Yoshida²

2007

Bulletin of the Chemical Society of Japan

370

127

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“…In this context, the observation of a "negative isotope effect" in κ-(BEDT-TTF) 2 Cu(NCS) 2 may be of great importance [22,23]; on replacing the terminal hydrogens of the BEDT-TTF molecule in κ-(BEDT-TTF) 2 Cu(NCS) 2 by deuterium, it was found that a small but consistent increase in the superconducting critical temperature T c occurred [22,23]. By contrast, isotopic substitutions of other heavier atoms in the BEDT-TTF molecule or in the anion layer exhibit a very small, normal isotope effect or no significant isotope effect at all, respectively [23].…”

mentioning

confidence: 99%

“…The experiments involved single crystals of κ-(BEDT-TTF) 2 Cu(NCS) 2 (∼ 0.7 × 0.5 × 0.1 mm 3 ; mosaic spread < ∼ 0.1 • ), produced using electrocrystallization [22,23]. In some of the crystals, the terminal hydrogens of the BEDT-TTF molecules were isotopically substituted by deuterium; we refer to these deuterated samples as d8, and conventional hydrogenated samples as h8.…”

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confidence: 99%

Comparison of the normal-state properties of -(BEDT-TTF)₂Cu(NCS)₂and its deuterated analogue in high magnetic fields and under high hydrostatic pressures

Biggs

Klehe²,

Singleton³

et al. 2002

J. Phys.: Condens. Matter

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Abstract. Details of the Fermi-surface topology of deuterated κ-(BEDT-TTF) 2 Cu(NCS) 2 have been measured as a function of pressure, and compared with equivalent measurements of the undeuterated salt. We find that the superconducting transition temperature is much more dramatically suppressed by increasing pressure in the deuterated salt. It is suggested that this is linked to pressure-induced changes in the Fermi-surface topology, which occur more rapidly in the deuterated salt than in the undeuterated salt as the pressure is raised. Our data suggest that the negative isotope effect observed on deuteration is due to small differences in Fermi-surface topology caused by the isotopic substitution.

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Determination of a mass isotope effect on Tc in an electron-donor-based organic superconductor, κ-(ET)2Cu(NCS)2, where ET represents bis(ethylenedithio)tetrathiafulvalene

Cited by 50 publications

References 28 publications

Electronic collective modes and superconductivity in layered conductors

Electronic collective modes and superconductivity in layered conductors

Development of Conductive Organic Molecular Assemblies: Organic Metals, Superconductors, and Exotic Functional Materials

Comparison of the normal-state properties of -(BEDT-TTF)₂Cu(NCS)₂and its deuterated analogue in high magnetic fields and under high hydrostatic pressures

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Determination of a mass isotope effect on Tc in an electron-donor-based organic superconductor, κ-(ET)2Cu(NCS)2, where ET represents bis(ethylenedithio)tetrathiafulvalene

Cited by 50 publications

References 28 publications

Electronic collective modes and superconductivity in layered conductors

Electronic collective modes and superconductivity in layered conductors

Development of Conductive Organic Molecular Assemblies: Organic Metals, Superconductors, and Exotic Functional Materials

Comparison of the normal-state properties of -(BEDT-TTF)2Cu(NCS)2and its deuterated analogue in high magnetic fields and under high hydrostatic pressures

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Product

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Comparison of the normal-state properties of -(BEDT-TTF)₂Cu(NCS)₂and its deuterated analogue in high magnetic fields and under high hydrostatic pressures