Conducting and Superconducting Crystals Based on Some Unsymmetrical Donor Molecules

Papavassiliou, George C.; Lagouvardos, D. J.; Kakoussis, V. C.; Mousdis, George A.; Terzis, Aris; Hountas, A.; Hilti, B.; Mayer, Carl; Zambounis, J. S.; Pfeiffer, Loren; Delhaès, P.

doi:10.1007/978-1-4899-2605-0_34

Cited by 18 publications

(28 citation statements)

References 11 publications

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“…1͒, which is a selenium analog of MDT-TTF ͑MDT-TTF: methylenedithio-tetrathiafulvalene͒, and have discovered superconductivity in the AuI 2 salt of MDT-TSF. 5 Although the only superconductor based on MDT-TTF ͓-(MDT-TTF) 2 AuI 2 ͔ has the structure with strong dimerization, 6 the AuI 2 salt of MDT-TSF has a uniform donor stacking along the a axis. However, the exact composition and the anion position of this salt have not been determined from the ordinary structure analysis.…”

mentioning

confidence: 99%

Organic superconductor with an incommensurate anion structure: (MDT−TSF)(AuI
Kawamoto
¹
,
Mori
²
,
Takimiya
³

et al. 2002
Phys. Rev. B
46
2
36
0
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The degree of charge transfer and the upper critical field of the organic superconductor ͑MDT-TSF͒(AuI 2) x have been investigated ͑MDT-TSF: methylenedithio-tetraselenafulvalene͒. The x-ray oscillation photograph indicates that the anion lattice is incommensurate with the donor lattice, and the chemical composition is ͑MDT-TSF͒(AuI 2) 0.44. The charge-transfer degree of this salt is 0.44. The electrical resistivity and the Seebeck coefficient indicate that this salt is a good Fermi liquid above the superconducting transition temperature. The upper critical fields show anisotropic three-dimensional character in spite of the complicated incommensurate structure, and are within the Clogston-Chandrasekhar paramagnetic limit in all directions.

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mentioning

confidence: 99%

Organic superconductor with an incommensurate anion structure: (MDT−TSF)(AuI
Kawamoto
¹
,
Mori
²
,
Takimiya
³

et al. 2002
Phys. Rev. B
46
2
36
0
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“…Besides TMTSF, TMTTF, BO, ET, and BETS superconductors, there are other superconductors (Scheme 7, numbers in bracket are the total members of each superconducting family and the highest Tc) of CT salts based on symmetric (BEDSe-TTF [140] and BDA-TTP [141][142][143][144]) and asymmetric donors (ESET-TTF [145], S,S-DMBEDT-TTF [146], meso-DMBEDT-TTF [147,148], DMET [149], DODHT [150], TMET-STF [151], DMET-TSF [152], DIETS [153], EDT-TTF [154], MDT-TTF [155,156], MDT-ST [157,158], MDT-TS [159], MDT-TSF [160][161][162][163], MDSe-TSF [164], DTEDT [165], and DMEDO-TSeF [166,167]). κ-(MDT-TTF)2AuI2 (Tc = 3.5 K) exhibited a Hebel-Slichter coherent peak just below Tc, indicating a BCS-type gap with s-symmetry [156].…”

Section: Superconductors Of Other Electron Donor Moleculesmentioning

confidence: 99%

Development and Present Status of Organic Superconductors

Saito¹,

Yoshida²

2012

Superconductors - Materials, Properties and Applications

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based on the two main requirements for the conductivity, namely, (1) a uniform segregated stacking of the same kind of component molecules, and (2) the fractional CT state (uniform partial CT) of the molecules. Since TTF•TCNQ has a low-dimensional segregated stacking, it showed a metal-insulator (MI) transition (Peierls transition) below about 60 K. For TTF•TCNQ, the Peierls transition occurs by the nesting of the one-dimensional Fermi surface causing lattice distortion associated with the strong electron-phonon interaction and forms charge density wave (CDW). There are also several one-dimensional organic metals which show MI transitions by the formation of spin density wave (SDW) when the periodicity of the SDW coincides with the nesting vector of Fermi surface and no lattice distortion occurs in this case. An increase in the electronic dimensionality is inevitable to prevent the nesting of Fermi surfaces and develop superconductors. Several attempts have been made through "pressure", "heavy atom substitution", or "peripheral addition of alkylchalcogen groups" (Fig. 1). The latter two correspond to the enhancement of the self-assembling ability of the molecules. Appropriate examples taking TTF derivatives are shown in Fig. 1. Based on TMTSF molecules several superconductors under pressure have been prepared with warped one-dimensional Fermi surface since 1980 (a in Fig. 1) [9-14]. In general, the ratio of transfer energies (t// / t ⊥) is larger than 3 for one-dimensional Fermi surface and a closed two-dimensional Fermi surface is formed when t// ≤ 3t ⊥ , where t// and t ⊥ are the transfer energies along the directions of the largest and second largest intermolecular interactions. The BO (BEDO-TTF) molecules afforded stable two-dimensional metals having two-dimensional Fermi surface (b in Fig. 1) owing to the strong self-assembling ability by intermolecular S•••S and hydrogen-bonds [15], and only two superconductors are known since 1990 (Tc ≤ 1.5 K). The substitution of an ethylenedioxy group with an ethylenedithio group (BO → ET (BEDT-TTF)) destabilized the metallic state of BO compounds and provided unstable two-dimensional conductors (c in Fig. 1). Consequently, variety of superconductors and other functional solids have been developed based on twodimensional metals of ET since 1982 (Tc ≤ 13.4 K) [16-20] and its analogues (Tc ≤ 10 K) [21]. Figure 1. Strategy for chemical modification of the TTF molecule to increase (arrows) or decrease (dotted arrow) the electronic dimensionality by the aid of enhancement or suppression of the selfassembling ability of the molecules, respectively [16]. Typical Fermi surfaces of TMTSF (a: (TMTSF)2NbF6), BO (b: (BO)2.4I3), and ET (c: β-(ET)2I3) CT solids are depicted.

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“…The ordered anions reside in the cavities of the tetragonal donor lattice (Figure 2). Calculations of difference Fourier maps during the structure solution process give electron density with appreciable values to be spread along the a or b crystallographic axis and in between the 2D donor layers, which is possible to be modeled with disordered AuCl 2 anions, "smeared" all along the b axis as in the case of the anions in other τ-phases [11]. As is mentioned in [10], these disordered chains of AuCl 2 anions are the origin of the intense diffusion streaks which are recorded on the diffraction images (Figure 3).…”

Section: Crystal Structure and Diffusion Scatteringmentioning

confidence: 99%

“…During recent years, a number of τ-phase conductors based on P-SS-DMEDT-TTF(1) and EDO-SS-DMEDT-TTF(2) molecules ( Figure 1) have been prepared and studied (see references [1][2][3][4][5][6][7][8][9][10][11]). Their general formulas are τ-(P-S,S-DMEDT-TTF) 2 (AuX 2 ) (AuX 2 ) y (abbreviated as 1X) and τ-(EDO-S,S-DMEDT-TTF) 2 (AuX 2 ) (AuX 2 ) y (abbreviated as 2X) with X = Cl, Br, I and y~0.75.…”

Section: Introductionmentioning

confidence: 99%

Structural and Electrical Properties of the τ-(P-S,S-DMEDT-TTF)2 (AuCl2) (AuCl2)y Compound with (y ≈ 0.9)

et al. 2012

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Abstract:The compound τ-(P-S,S-DMEDT-TTF) 2 (AuCl 2 ) (AuCl 2 ) y (where P-S,S-DMEDT-TTF is the compound pyrazino-(S,S)-dimethyl-ethylenedithio-tetrathiofulvale) crystallizes in the non-centrosymmetric space group I-42d, with a = 7.3260(1) Å and c = 67.5487(12) Å (RT data) and remains tetragonal in the temperature range from RT to 100 K. This compound is a quasi-two-dimensional material and the relation of the lattice of the order part of the structure created by the donor molecules with that of the disordered anion lattice revealed by intense diffusion streaks give a value of y ≈ 0.9. In contrast to the Br and I analogs or the related compounds which contain the compound ethylenedioxy-S,Sdimethylenedithiotetrathiafulvalene (abbreviated as EDO-S,S-DMEDT-TTF) as donor and which exhibit anisotropic metallic behavior down to low temperature, this compound is anisotropic semiconductor in the same temperature range. The appearance of satellites on the diffraction images recorded below 110 K indicates a structural change. Resistivity measurements show that this material is a semiconductor with anisotropy σ a /σ c of ca. 400-1400 at room temperature. OPEN ACCESSCrystals 2012, 2 1284

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Conducting and Superconducting Crystals Based on Some Unsymmetrical Donor Molecules

Cited by 18 publications

References 11 publications

Organic superconductor with an incommensurate anion structure: (MDT−TSF)(AuI
Kawamoto
¹
,
Mori
²
,
Takimiya
³

et al. 2002
Phys. Rev. B
46
2
36
0
View full text Add to dashboard Cite

Organic superconductor with an incommensurate anion structure: (MDT−TSF)(AuI
Kawamoto
¹
,
Mori
²
,
Takimiya
³

et al. 2002
Phys. Rev. B
46
2
36
0
View full text Add to dashboard Cite

Development and Present Status of Organic Superconductors

Structural and Electrical Properties of the τ-(P-S,S-DMEDT-TTF)2 (AuCl2) (AuCl2)y Compound with (y ≈ 0.9)

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Conducting and Superconducting Crystals Based on Some Unsymmetrical Donor Molecules

Cited by 18 publications

References 11 publications

Organic superconductor with an incommensurate anion structure: (MDT−TSF)(AuIKawamoto1, Mori2, Takimiya3 et al. 2002Phys. Rev. B462360View full textAdd to dashboardCite

Organic superconductor with an incommensurate anion structure: (MDT−TSF)(AuIKawamoto1, Mori2, Takimiya3 et al. 2002Phys. Rev. B462360View full textAdd to dashboardCite

Development and Present Status of Organic Superconductors

Structural and Electrical Properties of the τ-(P-S,S-DMEDT-TTF)2 (AuCl2) (AuCl2)y Compound with (y ≈ 0.9)

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Product

Resources

About

Organic superconductor with an incommensurate anion structure: (MDT−TSF)(AuI
Kawamoto
¹
,
Mori
²
,
Takimiya
³

et al. 2002
Phys. Rev. B
46
2
36
0
View full text Add to dashboard Cite

Organic superconductor with an incommensurate anion structure: (MDT−TSF)(AuI
Kawamoto
¹
,
Mori
²
,
Takimiya
³

et al. 2002
Phys. Rev. B
46
2
36
0
View full text Add to dashboard Cite