Physical Properties of Some ET-Based Organic Metals and Superconductors with Mercury Containing Anions

Metal-insulator transition in the dimerized organic conductor κ−(BEDT-TTF)2Hg(SCN)2Br

“…18,19 The present investigation now addresses the question in which way κ-(BEDT-TTF) 2 Hg(SCN) 2 X is modified when replacing X = Cl by Br in the anion sheet. Let us recall that in the case of κ-(BEDT-TTF) 2 Cu[N(CN) 2 ]Cl the corresponding substitution pushes the antiferromagnetic Mott insulator into a superconducting phase with T c ≈ 12 K. 1 The family of κ-(BEDT-TTF) 2 X salts with mercurybased anions have a structure similar to the Cu-salts, 20 but different ratios of transfer integrals, which result in modified parameters used to map them on the Hubbard model. 21 In particular the orbital overlap t d within the dimers of the Hg-compounds is weaker compared to the the Cu-family, causing a reduced on-site repulsion U with respect to the inter-dimer interaction.…”

High-Pressure Studies of Doped-Type Organic Superconductors

“…In this case, with increasing pressure, the electrons localized at the dimers of BEDT-TTF experience a first-order insulator-metal transition 2 and exhibit a Fermi-liquid behavior 3 immediately upon delocalization. (BEDT-TTF) 4 Hg 2.89 Br 8 is an ambient-pressure superconductor with a T c value of 4.3 K 5 . This salt is also known to crystallize into the -type structure 5 .…”

“…Indeed, this salt exhibits metallic temperature variations and superconductivity at 4.3 K 4 in spite of the highly enhanced U/W value (U/W = 1.79) 5 . In order to obtain information about the nature of the normal and superconducting states in this doped-type superconductor, we performed the detailed characterization of the transport properties of -(BEDT-TTF) 4 6,7 . Electrical resistivity measurements were performed with a standard four-probe method with the DC current parallel or perpendicular to the conducting layers under ambient and high pressures.…”

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-(BEDT-TTF) 4 Hg 2.89 Br 8 is an ambient-pressure superconductor with a transition temperature (T c ) value of 4.3 K. This salt can be considered as an electron system that is naturally carrier doped into a Mott insulator by a slight excalation of the Hg ions. In order to obtain information about the nature of the metallic and superconducting states in this doping system, we performed electrical resistivity measurements as functions of temperature and pressure.

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BEDT-TTF-based radical cation salt with the cyanurate anion: synthesis, structure, conductivity, and polarized reflection spectra

“…Most of radical cation salts were prepared with inorganic anions having different structures. [1][2][3] By contrast, organic anions have found little use. 4 This is associated with their reactivity and structural fea tures.…”