Eduard B. Yagubskii

Organic conductors, superconductors and magnets : from synthesis to molecular electronics

Macrocyclic, Molecular, and Supramolecular TTF Systems.- Design of Organic (Super)Conductors and Study of Their Physical Properties.- From Quasi-One-Dimensional Conductors Based on TCNQ Salts to the First Quasi-Two-Dimensional Superconductors at Ambient Pressure Based on BEDT-TTF Triiodides.- Organic-inorganic Hybrids: the Best of Both Worlds?.- Development of Single-Component Molecular Metals and Magnetic Molecular Superconductors.- Multiproperties Molecular Materials: Synergy between Electrical Conductivity and Magnetic Interactions.- Unconventional Properties of TTF-Based Organic Magnetic Conductors.- Multifuctionality in Molecular Conductors and Magnets.- Near-IR Spectroscopy as A Tool To Monitor The Purification of Single-Walled Carbon Nanotube Films by Thermal Oxidation.- Metal Fulleride Salts: Prototypes of Highly Correlated Molecular Systems.- Magnetic Molecules.- Nanoengineering Route to Two-Dimensional Hybrid Materials.- Physical Properties of Thin Molecular Organized Films.- The Role of Organic Conductors in a World of Nanoscience.- Thin Films and Nano-Objects of Molecule-Based Materials.- Three Unimolecular Rectifiers and a Proposed Unimolecular Amplifier.- The Design, Characterization and Use of Molecules in Molecular Devices.

Superconductivity in reticulate doped polycarbonate films, containing (BEDT-TTF)2I3

Abstract Electric properties of conducting reticulate doped polymeric films, containing ET polyiodide crystalline network, have been investigated. In order to improve their conducting properties they were annealed in iodine vapors. It was found, that certain conditions of thermal treatment lead to metal-like state, stable down to helium temperatures. The overall decrease of resistivity R 300K /R 4.2K reaches 45. At some conditions of the thermal treatment an accelerated decrease of resistivity is observed below 7 K, vanishing with application of magnetic field, thus giving the first evidence of the (incomplete) superconducting transition in polymeric organic composite material.

Novel organic superconductor κ-(ET)2Cu[N(CN)2]Cl0.5Br0.5 with Tc∼11.3 K

κ-(ET)2Cu[N(CN)2]Cl0.5Br0.5, a new organic superconductor (Tc ∼ 11.3 K at ambient pressure) has been synthesized. Its X-ray study has been undertaken.

Effect of electrocrystallization medium on quality, structural features, and conducting properties of single crystals of the (BEDT-TTF)4AI[FeIII(C2O4)3]·G family

A modified procedure for the electrocrystallization of organic conductors with paramagnetic anions of the (BEDT-TTF)4AI[MIII(C2O4)3]·G family has been proposed. It is found that single crystals of different phases of the family can be prepared if the electrocrystallization medium is represented by the mixture of 1,2,4-trichlorobenzene (or 1,3-dibromobenzene), 96% ethanol and different solvents (G), only the latter being included into the composition of the resulting salts as neutral guest molecules (G = benzonitrile, fluorobenzene, chlorobenzene, 1,2-dichlorobenzene, bromobenzene, nitrobenzene). Using this approach, a number of known and new BEDT-TTF salts with the tris(oxalato)ferrate anion have been synthesized. Among them, there are superconducting crystals of monoclinic β′′-series with different guest solvents (G) and their mixtures. For the first time, crystals of a triclinic phase (G = 1,2-dibromobenzene), with alternating α- and ‘pseudo-κ’ BEDT-TTF layers and metallic behaviour down to 1.5 K, were obtained. Additionally, monoclinic crystals having another stoichiometry and α-type donor packing were prepared.

Molecular metals based on Pd(dddt)2 and Ni(dddt)2 complexes

Abstract A series of electroconducting cationic salts based on the Pd(dddt) 2 and Ni(dddt) 2 complexes has been synthesized. The first stable molecular metals have been found among the M(dddt) 2 salt family.

Optical study of the electronic structure and electron-molecular vibrational coupling in a novel organic superconductor κ-(BEDT-TTF)2Cu[N(CN)2]Cl0.5Br0.5

Abstract Reflectance spectra of a new ambient-pressure superconductor, κ-(BEDT-TTF) 2 Cu[N(CN) 2 ]Cl 0.5 Br 0.5 ( T c = 11.3 K), where BEDT-TTF is bis(ethylenedithio)tetrathiafulvalene, are measured in the range from 750 to 5500 cm −1 and from 9000 to 40 000 cm −1 for different polarizations. The detailed analysis of the infrared conductivity, obtained after a Kramers-Kronig transformation, is performed in the framework of the approach, based on the ‘phase phonons’ theory of M.J. Rice, with the help of special transformation of the experimental data. Parameters of the electronic subsystem and electron-molecular vibration coupling are determined. The determined ‘total’ dimensionless coupling constant (λ) is compared with those of the organic superconductors κ-(BEDT-TTF) 2 Cu(NCS) 2 ( T c = 10.4 K) and (BEDT-TTF) 4 Hg 2.89 Br 8 ( T c = 4.3 K). It is found that a larger λ produces a larger T c in accordance with the known Bardeen-Cooper-Schriffer formula for T c .

Electronic structure and electron-molecular vibrational coupling in organic superconductors ET4Hg2.89Br8 and ET2Cu(NCS)2: comparative studies by optical spectroscopy

Abstract Reflectance spectra of organic superconductors ET 4 Hg 2.89 Br 8 and ET 2 Cu(NCS) 2 are measured in the range from 650 to 40 000 cm −1 for different polarizations. The reflectance is analysed in the framework of the ‘phase phonons’ theory of M. J. Rice with the help of special transformation of the experimental data. Parameters of the electronic subsystem and of electron-molecular vibration coupling are determined. The role of anion-cation interaction is shown to be important for the onset of superconductivity.

π-Donor BETS Based Bifunctional Superconductor with Polymeric Dicyanamidomanganate(II) Anion Layer : κ-(BETS)2Mn[N(CN)2]3

Crystals of the bis(ethylenedithio)tetraselenafulvalene (BETS) radical cation salt with dicyanamidomanganate(II) anion, kappa-(BETS)2Mn[N(CN)2]3, were synthesized, which combine conducting and magnetic properties at ambient pressure and are superconducting (Tc approximately/= 5 K) at a moderate pressure of 0.3 kbar.

Transport properties and giant Shubnikov-de Haas oscillations in the first organic conductor with metal complex anion containing selenocyanate ligand, (ET)2 T1Hg(SeCN)4

Abstract Temperature dependence of the resistivity in various crystallographic directions and high pulsed field magnetoresistance of organic metal α-(ET) 2 TlHg(SeCN) 4 have been studied at temperatures down to 80 mK. Giant Shubnikov-de Haas oscillations, which are attributed to the two-dimensional nature of the cylindrical Fermi surface with a very small warping along the direction of the lowest conductivity have been observed. Four harmonics of the fast oscillations with fundamental frequency F 0 = 653 ± 3 T and slow frequency oscillations with F s = 38 ± 5 T have been revealed.

Factors affecting the metallic versus semiconducting properties of charge transfer salts containing [M(dddt)2]2 and [M(dmit)2]2 (M = Pd, Pt) dimers

Abstract To understand the structural and electronic factors controlling the metallic versus semiconducting properties of the β-type charge transfer salts containing the [M(dddt)2]2+ and [M(dmit)2]2- (M = Pd, Pt) dimer units, we calculated their tight-bindinf electronic band structures. Our analysis shows that the partially filled band of both types of salts is derived either from the HOMO or from the LUMO of their monomer unit depending upon the extent of dimerization. A good electrical conductivity is expected for strongly dimerized M(dmit)2 systems and for weakly dimerized M(dddt)2 systems.