Superconductivity in k-

Sushko YV, Ito H, Ishiguro T, Horiuchi S, Saito G (1993) Reentrant superconductivity in k-(BEDT-TTF)2Cu[N(CN)2]C1 and its pressure phase diagram. Solid State Commun 87 997-1000... 

Kodani M, Takamori A, Takimiya K, Aso Y, Otsubo T (2002) Novel conductive radical cation salts based on methylenediselenotetraselenafulvalene (MDSe-TSF) a sign of superconductivity in K-(MDSe-TSE)2Br below 4 K. J Solid State Chem 168 582-589... 

Maesato M, Shimizu Y, Ishikawa T, Saito G, Miyagawa K, Kanoda K (2004) Spin-liquid behavior and superconductivity in k-(BEDT-TTF)2X the role of uniaxial strain. J Phys IV 114 227-232... 

The molecule Ceo was first observed in the mass spectrum of laser evaporated carbon by Kroto et al., who proposed the now familiar soccer ball stmcture. Subsequently, macroscopic quantities were synthesized. In the solid state, Ceo adopts a face-centered cubic (fee) stmcture, which can be considered to be based on the close packing of spheres with a radius of 5 A. Two tetrahedral sites and one octahedral site with radii 1.12 and 2.06 A are present in the stmcture. The availability of these empty sites and the electronegativity of Ceo make it a suitable host lattice for reductive intercalation by electropositive cations such as the alkah metals. The octahedral site is larger than any of the alkah cations, but the tetrahedral site is about the same size as Na+. The discovery of Superconductivity in K Ceo (Tc = 18K) has focused considerable interest on these materials. Intercalation compounds can be prepared by direct reaction of the alkali metal with Ceo to form compositions Aj,C6o (x = 2, 3, 4, or 6) depending on the specific A cation. Direct reaction of Ceo with the alkali metals is the most conveiuent route to the AeCeo phases other compositions can be prepared by use of the appropriate stoichiometry or by reaction of AeCeo with Ceo. Other alkali metal reagents such as NasHg2 and NaH have also been used. ... 

The universally accepted tests for superconductivity, namely a transition to zero resistance and a Meissner effect showing the expulsion of magnetic field, demonstrate unequivocally the existence of superconductivity in K Cso. The 18-K transition temperature is the highest yet reported for a molecular superconductor. This may be compared with the previously reported occurrence of superconductivity at 0.55 K in potassium-intercalated graphite. We expect that optimization of composition and crystallinity will lead to further improvement in the superconducting properties. ... 

Shimizu K, Suhara K, Ikumo M, Eremets M I and Amaya K 1998 Superconductivity in oxygen Nature 393 767... 

Special Alloys. AHoys of tin with the rater metals, such as niobium, titanium, and 2kconium, have been developed. The single-phase alloy Nb Sn [12035-04-0] has the highest transition temperature of any known superconductor (18 K) and appears to keep its superconductivity in magnetic... 

G. Bednorz and K. A. Miiller (Zurich) for their important breakthrough in the discovery of superconductivity in ceramic materials. 

Superconductivity in Complex Systems Volume Editors Muller, K. A., Bussmann-Holder, A. 

In the SRM-768, this effect is reduced by spot welding small pieces of A1 to the W and Be samples. The Al, with its Tc = 1.18 K, serves as a nucleation centre to induce superconductivity in the samples by proximity effect (see Section 15.2.2). 

The discovery of superconductivity in heavily B-doped diamond, which produces p-type material, has provoked interest in using nB and 10B NMR for characterization. The nB static NMR at 4.2 K of heavily-doped diamond (2.8-8.7 x 1021 B/cm3) showed two unresolved peaks, the sharper of which was... 

Fig. 3 Ambient-pressure superconductivity in a-(EDT-TTF) [Ni(dmit)2]. The inset shows the superconductive transition at 1.3 K. Redrawn after [42]...

Jerome D, Mazaud A, Ribault M, Bechgaard K (1980) Superconductivity in a synthetic organic conductor, (TMTSF)2PF6. J Phys Lett 41 L95-L97... 

Lai.85Ba0.i5CuO4) lost its resistance at a Tc = 30-35 K. The observation of superconductivity in a metal oxide at temperatures higher than those of metals themselves triggered a change in emphasis in superconductivity research towards this type of material. In 1987 two research groups, at the University of Houston and the University of Alabama, reported that the oxide of formula YBa2Cu307 x (commonly known as T-2-3 superconductor , from the stoichiometric ratios Y Ba Cu of 1 2 3) displayed a Tc of 92 K. 

A. Shengelaya, S. Reich, Y. Tsabba, and K. A. Muller, Electron spin resonance and magnetic susceptibility suggest superconductivity in Na doped WO3 samples, Eur. Phys. J. B 12(1), 13-15 (1999). 

V. V. Struzhkin, E. Gregoryanz, H. K. Mao, R. J. Hemley, and Y. A. Timofeev, New methods for investigating superconductivity , in High Pressure Phenomena, Koceedings of the International School of Physics Enrico Eermi, Course CXLVII, R. J. Hemley, G. L. Chiarotti, M. Bemasconi, and L. Ulivi, eds. lOS Press, Amsterdam, 2002, p. 275. 

Yvon, K. (1982) in Superconductivity in Ternary Compounds I, Eds. O. Fischer and M. B. Maple, Springer-Verlag, Berlin, pp. 25-86. 

Those readers not familiar with superconductivity in organic materials may find the Tc values rather low. However, they are comparable to values for inorgaiuc metallic elements. Here is a list of some selected examples FcCNb) = 9.25 K, rc(Pb) = 7.20 K, rc(a-Hg) = 4.15 K, rc(Sn) = 3.72 K, Tc(Al) = 1.17 K, Tc(ri) = 0.40 K, etc. It is interesting to note that copper does not exhibit a superconducting transition. The highest known Tc values of any material correspond to the copper-oxide series with Tc 138 K as the absolute record for the thallium-doped mercury-cuprate compound. 

Doping-induced superconductivity in MOMs has been demonstrated, e.g., for Ceo, where CSjRb),C6o reaches Tg values as high as 33 K (Tanigaki et al, 1991). 

Iwasaki E, Shimizu K, Amaya K, Nakayama A, Aoki K, Carlon RP (2001) Metallization and superconductivity in hexaiodobenzene under high pressure. Synth Met 120 1003-1004... 

Amaya K, Shimizu K, Takeshita N, Eremets MI, Kobayashi TC, Endo S (1998) Observation of pressure-induced superconductivity in the megabar region. J Phys Condens Matter 10 11179-11190... 

Schirber JE, Overmyer DL, Carlson KD, Williams JM, Kini AM, Wang HH, Charlier FIA, Love BJ, Watkins DM, Yaconi GA (1991) Pressure-temperature phase diagram, inverse isotope effect, and superconductivity in excess of 13 K in /c-(BEDT-TTF)2Cu[N(CN)2]Cl, where BEDT-TTF is bis(ethylenedithio)tetrathiafulvalene. Phys Rev B44 4666-4669... 

Sakata J, Sato H, Miyazaki A, Enoki T, Okano Y, Kato R (1998) Superconductivity in new organic conductor K-(BEDSe-TTE)2CuN(CN)2Br. Solid State Commun 108 377-381... 

Kikuchi K, Murata K, Honda Y, NamUd T, Saito K, Ishiguro T, Kobayashi K, Ikemoto I (1987) On ambient-pressure superconductivity in organic conductors electrical properties of (DMET)2l3, (DMET)2l2Br and (DMET)2lBr2. J Phys Soc Jpn 56 3436-3439... 

Takimiya K, Kodani M, NiUiara N, Aso Y, Otsubo T, Bando Y, Kawamoto T, Mori T (2004) Pressure-induced superconductivity in (MDT-TS)(Aul2)o.44i [MDT-TS = 5H-2-(l,3-diselenol-2-ylidene)-l,3,4,6-tetrathiapentalene] anew organic superconductor possessing an incommensurate anion lattice. Chem Mater 16 5120-5123... 

Nomura K, Muraoka R, Matsunaga N, Ichimura K, Yamada J (2009) Anisotropic superconductivity in j8-(BDA-TTP)2SbF6 STM spectroscopy. Physica B 404 562-564... 

Konoike T, Uji S, Terashima T, Nishimura M, Yasuzuka S, Enomoto K, Eujiwara H, Zhang B, Kobayashi H (2004) Magnetic-field-induced superconductivity in the antiferromagnetic organic superconductor K-(BETS)2peBr4. Phys Rev B70 094514/l-5... 

Clark K, Hassanien A, Khan S, Braun KF, Tanaka H, FQa SW (2010) Superconductivity in just four parrs of (BETS)2GaCl4 molecules. Nat Nanotechnol 5 261-265... 

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