Superconductivity at 14.2 K in Layered Organics under Extreme Pressure

Taniguchi, Hiromi; Miyashita, M.; Uchiyama, Kenichi; Satoh, Kazuhiko; Môri, N.; Okamoto, Hiroyuki; Miyagawa, Kazuya; Kanoda, K.; Hedo, Masato; Uwatoko, Yoshiya

doi:10.1143/jpsj.72.468

Cited by 183 publications

(119 citation statements)

References 29 publications

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“…A similar tendency was observed in κ-(BEDT-TTF) 2 Cu(NCS) 2 [31]. The heat capacity results at extremely low temperature regions were consistent with the temperature dependence of T 1 −1 probed by 13 C-NMR experiments, demonstrating the d-wave paring from the observation of the T 3 term in the superconductive state [32][33][34]. The thermal conductivity result reported in ref.…”

Section: K Class Superconductors: κ-(Bedt-ttf) 2 Cu(ncs) 2 and κ-(supporting

confidence: 87%

“…According to the result of single crystal calorimetry, this compound does not show any γ and relatively smaller lattice heat capacity expressed by smaller β = 7.46 mJ K −4 mol −1 . This compound was known to convert to 14.6 K superconductor under strong pressure of about 80 GPa observed by Taniguchi et al [13].…”

Section: Antiferromagnetic Mott Insulator Regionmentioning

confidence: 89%

“…Antiferromagnetic long-range orderings due to the weak intra-layer magnetic interaction were observed by the splitting of line shapes of 13 C-NMR and the existence of an interanl field by µSR measurements. An important point for discussing the electronic properties of the insulating salts by the thermodynamic measurements is whether the peak associated with the long-range ordering exists or not.…”

Section: Antiferromagnetic Mott Insulator Regionmentioning

confidence: 99%

“…It is emphasized that the magnitude of the γ values are enhanced up to 55 mJ K −2 mol −1 for HgBr and 52 mJ K −2 mol −1 for HgCl. Kurosaki et al [48] observed by 13 C-NMR that antiferromagnetic fluctuations are much enhanced from the usual κ-(BEDT-TTF) 2 X system anomalously down to the dilution temperature region. The enhancement of static parameters observed by heat capacity and magnetic susceptibility and T 1 −1 means that the effective mass is enhanced due to the electron correlations, just as in the case of itinerant magnetic systems in intermetallic compounds based on 3d transition metal and 4f, 5f heavy ferimion electron systems.…”

Section: κ-(Bedt-ttf) 2 Ag(cn) 2 H 2 O and κ-(Mdt-ttf) 2 Auimentioning

confidence: 99%

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Thermodynamic Properties of κ-(BEDT-TTF)2X Salts: Electron Correlations and Superconductivity

Nakazawa

2012

Crystals

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Abstract:Heat capacity measurements of κ-(BEDT-TTF) 2 X (BEDT-TTF: Bis(ethylendithio) tetrathiafulvalene, X: counteranions) which are classified as two-dimensional (2D) dimer-Mott system are reported. At first, we explain structural and electronic features originated from rigid dimerization in donor arrangement in 2D layers. The antiferromagnetic Mott insulating phase located at low-pressure region in the phase diagram shows vanishing γ electronic heat capacity coefficient in the heat capacity, which claims opening of a charge-gap in this insulating state. Then, a systematic change of the γ around the Mott boundary region is reported in relation to the glass freezing of ethylene dynamics. The thermodynamic parameters determined by ∆C p /γT c of 10 K class superconductors, κ-(BEDT-TTF) 2 Cu(NCS) 2 and κ-(BEDT-TTF) 2 Cu[N(CN) 2 ]Br demonstrate that a rather large gap with a strong coupling character appears around the Fermi-surface. On the other hand, the low temperature heat capacity clearly shows a picture of nodal-gap structure due to an anisotropic pairing. The comparison with lower T c compounds in the κ-type structure is also performed so as to discuss overall features of the κ-type superconductors. The heat capacity measurements of hole-doped systems containing mercury in the counteranions show an anomalous enhancement of γ, which is consistent with the T 1 −1 of NMR experiments etc. The results of heat capacity measurements under high pressures are also reported. OPEN ACCESSCrystals 2012, 2 742

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Section: K Class Superconductors: κ-(Bedt-ttf) 2 Cu(ncs) 2 and κ-(supporting

confidence: 87%

Section: Antiferromagnetic Mott Insulator Regionmentioning

confidence: 89%

Section: Antiferromagnetic Mott Insulator Regionmentioning

confidence: 99%

Section: κ-(Bedt-ttf) 2 Ag(cn) 2 H 2 O and κ-(Mdt-ttf) 2 Auimentioning

confidence: 99%

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Thermodynamic Properties of κ-(BEDT-TTF)2X Salts: Electron Correlations and Superconductivity

Nakazawa

2012

Crystals

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“…β'-(BEDT-TTF) 2 ICl 2 shows superconductivity under ultra-high pressure (8 GPa) [56]. Under ambient pressure, this salt is an insulator and undergoes an anti-ferromagnetic (AF) transition at low temperature.…”

Section: Determination Of the Magnetic Moment In β'-(Bedt-ttf) 2 Iclmentioning

confidence: 99%

Magnetic and Electric Properties of Organic Conductors Probed by 13C-NMR Using Selective-Site Substituted Molecules

2012

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Quasi-One and quasi-two dimensional organic conductors consisting of TTF derivatives such as BEDT-TTF (bis-(ethylene-dithio)-tetra-thia-fulvalene) and TMTCF (C = S; TMTTF: tetra-methyl-tetra-thia-fulvalene, C = Se; TMTSF: tetra-methyl-tetraselena-fulvalene) have been well investigated in condensed matter physics because of interest in the emerging electric and magnetic properties, such as the spin density wave, charge order, superconductivity, anti-ferromagnetism, and so on. To probe the electronic state, nuclear magnetic resonance (NMR) is one of the most powerful tools as the microscopic magnetometer. A number of 13 C-NMR studies have been performed of the double-site central 13 C= 13C bond substituted molecules. However, problems with the coupled spin system of 13 C= 13 C complicated the interpretation for observations on NMR.Therefore, single-site 13 C-enriched molecules are desired. We summarize the problem of Pake doublet and the preparation of the single-site 13 C-susbstituted BEDT-TTF and TMTCF molecules. We also demonstrate the superiority of 13 C-NMR of the single-site 13 C-susbstituted molecule utilizing the hyperfine coupling tensor.

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Molecular Inorganic Conductors and Superconductors

Valade

Tanaka

2010

Molecular Materials

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Superconductivity at 14.2 K in Layered Organics under Extreme Pressure

Cited by 183 publications

References 29 publications

Thermodynamic Properties of κ-(BEDT-TTF)2X Salts: Electron Correlations and Superconductivity

Thermodynamic Properties of κ-(BEDT-TTF)2X Salts: Electron Correlations and Superconductivity

Magnetic and Electric Properties of Organic Conductors Probed by 13C-NMR Using Selective-Site Substituted Molecules

Molecular Inorganic Conductors and Superconductors

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