Overview of organic superconductor κ-(BEDT-TTF)2[Cu(NCS)2] and its related materials (original) (raw)
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Acta Crystallographica Section B Structural Science, 1995
Anion Disorder in the 115-118 K Structures of the Organic Superconductors KL-(BEDT-TTF)2Cu(CF3)4(C2H3CI3) and KL-(BEDT-TTF)2Ag(CFa)4(C2HaCI 3) [BEDT-TTF-3,4;3',4'-Bis(ethylenedithio)-2,2',5,5'-tetrathiafulvalene]
Synthetic Metals, 1997
A new approach to the synthesis of organic superconductors has recently been pioneered which involves the use of large, discrete, molecular anions as the charge-compensating entities in these charge transfer salts. The organic electron-donor molecule bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF or ET) has been electrocrystallized with the novel organometallic M(CF 3 ) 4~ (M = Cu, Ag, and Au) anions in a variety of 1,1,2-trihaloethane solvents. Over twenty organic superconductors have been synthesized which can be described by the general formula (ET)2Af(CF 3 ) 4 (l,l,2-trihaloethane). These solvated salts are shown to have highly anisotropic physical properties which can be tuned via modifications of each of their three molecular components: ET electron donor molecule, M(CF 3 ) 4ã nion, and neutral 1,1,2-trihaloethane solvent molecule. Superconductivity has also been observed in an ET salt containing the discrete SF5CH 2 CF2SO 3~ anion with an onset temperature near 5.2 K.
Organic superconductors revisited
The European Physical Journal B, 2009
Organic superconductors revisited STM imaging and DFT based simulations of the bc plane of κ-(BEDT-TTF) 2 Cu(NCS) 2
Contrasted structural properties of organic superconductors
Synthetic Metals, 1987
We present structural studies of organic conductors and superconductors of the (TMTSF)2X and (BEDT-TTF)2X families. These materials undergo a large variety of structural phase transitions like ordering of non-centrosymmetric anions Xin the (TMTSF)2X salts and commensurate ((BEDT-TTF)2Re04) or incommensurate (8(BEDT-TTF)213, (TMTSF)2SCN) lattice modulations. We shall pay special attention on new results concerning the pressure induced anion-ordering transformation in (TMTSF)2ReO 4 and the two competing phase transitions of (TMTSF)2PF202.
New ET-based organic superconductors with the organometallic anion Cu(CF3)4−
Synthetic Metals, 1995
Electrocrystallization of bis(ethylenedithio)tetrathiafulvalene (ET) with (PNP)Cu(CF3) 4 in 1,1,2-trichloroethane (TCE) results in two new superconductors, ~L-(ET)2Cu(CFa)4"(TCE), 1, with T c = 4.0 K, and KH-(ET)2Cu(CF3)4'(TCE)x, 2, with T c = 9.2 K. 1 forms well-developed plate-like crystals whose structure was determined by X-ray crystallography. Its band electronic structure is reported. The *q-i-phase forms long, thin needle bundles.
Inorganic chemistry, 2017
A new molecular superconductor, β″-(BEDT-TTF)2[(H2O)(NH4)2Cr(C2O4)3]·18-crown-6, has been synthesized from the organic donor molecule BEDT-TTF with the anion Cr(C2O4)33-. The crystal structure consists of conducting organic layers of BEDT-TTF molecules which adopt the β″ packing motif (layer A), layers of NH4+ and Λ-Cr(C2O4)33- (layer B), layers of (H2O)(NH4)18-crown-6 (layer C), and layers of NH4+ and Δ-Cr(C2O4)33- (layer D) which produce a superstructure with a repeating pattern of ABCDABCDA. As a result of this packing arrangement, this is the 2D superconductor with the widest gap between conducting layers where only a single donor packing motif is present (β″). Superconducting critical temperatures at ambient pressure observed by electrical transport and magnetic measurements are 4.0-4.9 and 2.5 K, respectively. The strong 2D nature of this system, the broad transition to Tzero at 1.8K, and the transition of α of V ∝ Iα from 1 to 3 on I-V curves strongly suggest that the superco...
2011
The k-(BEDT-TTF)X superconducting salts, [where BEDT-TTF is bis(ethylenedithio)-tetrathiafulvalene, abbreviated as ET, and X is a monovalent anion like Cu[N(CN) ]Br 2 , and for either Cu[N(CN) ]Cl 2 or ()2 Cu NCN and so on], exhibit interestinmagnetic and superconducting phase transitions [1]. They are quasi-two-dimensional and the interplane coupling is very weak. The basic structural unit is a dimer consisting of two BEDTTTF molecules stacked on top of one another. This layered structure leads to highly anisotropic electronic properties. These organic superconductors have similar characteristic superconducting properties including the intrinsic Josephson Effect and the mixed-state properties. This similarity suggests the existence of the vortex phase transition in the organic layered superconductors as observed in HTSC. Because the temperature scale is much lower in organic materials, the thermal fluctuation is expected to be small compared to HTSC. Thus, the comparison between th...
Physical Review B, 2002
We report high-sensitivity ac susceptibility measurements of the penetration depth in the Meissner state of the layered organic superconductor-(BEDT-TTF) 2 Cu͓N(CN) 2 ͔Br. We have studied nominally pure single crystals from the two different syntheses and employed controlled cooling procedures in order to minimize intrinsic remnant disorder at low temperatures associated with the glass transition, caused by ordering of the ethylene moieties in BEDT-TTF molecule at T G ϭ75 K. We find that the optimal cooling procedures ͑slow cooling of Ϫ0.2 K/h or annealing for 3 days in the region of T G) needed to establish the ground state depend critically on the sample origin, indicating different relaxation times of terminal ethylene groups. We show that, in the ground state, the behavior observed for nominally pure single crystals from both syntheses is consistent with unconventional d-wave order parameter. The in-plane penetration depth in (T) is strongly linear, whereas the out-of-plane component out (T) varies as T 2. In contrast, the behavior of single crystals with long relaxation times observed after slow (Ϫ0.2 K/h) cooling is as expected for a d-wave superconductor with impurities ͓i.e., in (T)ϰ out (T)ϰT 2 ] or might be also reasonably well described by the s-wave model. Our results might reconcile the contradictory findings previously reported by different authors.
Superconducting state in the layered organic superconductor κ-(BEDT-TTF)2Cu[N(CN)2]Br
Synthetic Metals, 1999
We summarize the main features of the magnetic field-temperature phase diagram for the superconducting state of K-(BEDT-TIl?)#&~(CN)JBr. The initial temperature dependence of the real component of ac susceptibility for field parallel and perpendicular to the ac plane are markedly different. The out-of-plane penetration depth Ai, and the related superfluid density vary at low tempeartures as T'. Slow flux dynamics below the irreversibility line for the ac field perpendicular to the BEDT-TTF planes might be ascribed to a vortex-pair creation process. The characteristic relaxation time 5 ~10'~ s is thermally activated with an activation energy of about 300K.