Organic Superconductors: when correlations and magnetism walk in

This survey provides a brief account for the start of organic superconductivity motivated by the quest for high Tc superconductors and its development since the eighties'. Besides superconductivity found in 1D organics in 1980, progresses in this field of research have contributed to better understand the physics of low dimensional conductors highlighted by the wealth of new remarkable properties. Correlations conspire to govern the low temperature properties of the metallic phase. The contribution of antiferromagnetic fluctuations to the interchain Cooper pairing proposed by the theory is borne out by experimental investigations and supports supercondutivity emerging from a non Fermi liquid background. Quasi one dimensional organic superconductors can therefore be considered as simple prototype systems for the more complex high Tc materials.Comment: 41 pages, 21 figures to be published in Journal of Superconductivity and Novel Magnetis

TTF based molecular magnets : Structural and physical properties of new salts involving the [Cr(NCS)(phen)] anion

Our group has recently focused on obtaining new molecular magnets based on radical BEDT-TTF or TTF derivatives. In these series, the aim is to combine the magnetic and conducting properties in the same material via the radical donor. We report here the structural and the physical properties of three salts with donors TTF (ferrimagnetic insulator), TMTTF (antiferromagnetic insulator) and TMTSF (paramagnetic semiconductor), containing the Reinekes anion derivative [Cr(NCS)4(phenanthroline)]. The role of the crystal packing in determining the physical properties is discussed

TTF based molecular magnets : Structural and physical properties of new salts involving the [Cr(NCS)(phen)] anion

Our group has recently focused on obtaining new molecular magnets based on radical BEDT-TTF or TTF derivatives. In these series, the aim is to combine the magnetic and conducting properties in the same material via the radical donor. We report here the structural and the physical properties of three salts with donors TTF (ferrimagnetic insulator), TMTTF (antiferromagnetic insulator) and TMTSF (paramagnetic semiconductor), containing the Reinekes anion derivative [Cr(NCS)4(phenanthroline)]. The role of the crystal packing in determining the physical properties is discussed

β″-(BEDT-TTF)[(HO)Cr(CO )]CHCl: Effect of included solvent on the structure and properties of a conducting molecular charge-transfer salt

The new charge-transfer salt β″-(BEDT-TTF)[(HO)Cr(CO )]S, where BEDT-TTF = bis-(ethylenedithio)tetrathiafulvalene and S = CHCl has a broad metal-insulator transition at approximately 150 K. This differs from similar salts in the BEDT-TTF tris(oxalato) metalate series, notably the superconducting materials with S = PhCN and the salt with S = CHN, which has a sharp metal-insulator transition

β″-(BEDT-TTF)[(HO)Cr(CO )]CHCl: Effect of included solvent on the structure and properties of a conducting molecular charge-transfer salt

The new charge-transfer salt β″-(BEDT-TTF)[(HO)Cr(CO )]S, where BEDT-TTF = bis-(ethylenedithio)tetrathiafulvalene and S = CHCl has a broad metal-insulator transition at approximately 150 K. This differs from similar salts in the BEDT-TTF tris(oxalato) metalate series, notably the superconducting materials with S = PhCN and the salt with S = CHN, which has a sharp metal-insulator transition

Structures and physical properties of BEDT-TTF salts containing channels of protons

Charge transfer salts with stoichiometry β″-(BEDT-TTF) [M(CO),](18-crown-6 ether)(9HO), where M= Cr, Ga or Fe and x= 2 or 3 are reported. Their structures suggest that proton migration is possible. Variable temperature resistivity measurements on the Cr salt show metallic behaviour down to 180K. Magnetic susceptibility of the Cr salt is paramagnetic down to 1.8 K. Preliminary impedance measurements suggest that the proton conductivities of the Cr and Ga salts are the order of 10 S cm at 300 K. © 2003 Elsevier Science B.V. All rights reserved

Effect of included guest molecules on the normal state conductivity and superconductivity of beta''-(ET)(4)[(H(3)O)Ga(C(2)O(4))(3)].G (G = pyridine, nitrobenzene).

Normal state conductivity and superconductivity together with bulk magnetic susceptibility and magnetization measurements have been measured for two molecular charge-transfer salts: beta' '-(ET)4[(H3O)Ga(C2O4)3]G (ET = bis(ethylenedithio)tetrathiafulvalene, G = pyridine for compound I and nitrobenzene for compound II). With the exception of the included guest molecules (G) the crystal structures are almost identical. Both show minima in their electrical transport at 130 K for I and at 160 K for II, but at lower temperatures their behaviors differ markedly. The resistance of I reaches a maximum at 50 K with a further small peak at 2 K and possible superconductivity only below 2 K, whereas that of II increases continuously down to 7.5 K, where an abrupt transition to a superconducting state occurs