Dresden 2011 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 10: Poster Session: Superconductivity
TT 10.32: Poster
Monday, March 14, 2011, 14:00–18:00, P4
Enhanced Tc in a Dual-Layered Molecular Superconductor — •Mariano de Souza1, Leonor Wiehl2, John A. Schlueter3, and Michael Lang1 — 1Physikalisches Institut, J.W. Goethe-Universität, SFB/TR49, D-60438 Frankfurt (M), Germany — 2Institut für Geowissenschaften, J.W. Goethe-Universität, D-60438 Frankfurt (M), Germany — 3Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
We have revisited the structural and electronic properties of the filamentary organic superconductor (BEDT-TTF)2Ag(CF3)4(TCE), first synthesized in 1994 [1]. Detailed structural investigations reveal that the BEDT-TTF molecules are arranged in two distinctly different packing motifs, κ and α′, which alternate from layer to layer [2]. This molecule-based superconductor with dual BEDT-TTF packing motifs has a Tc five times higher than that of its polymorph that contains only κ-type packing. Using the established empirical correlations between the bond lengths (C–S and C=S) and the oxidation state of the BEDT-TTF molecule, we have found that there is a uniform charge distribution in the κ-layers (corresponding to an oxidation state of +0.5 for all BEDT-TTF molecules), whereas in the α′-layer, half of the molecules are nearly fully oxidized to +1, while the other half are close to neutral, resulting in a charge-ordered neutral layer. These findings indicate that this material can be considered as a promising candidate for a distinctly two-dimensional superconductor.
J. A. Schlueter et al., Physica C 233, 379 (1994).
J. A. Schlueter et al., J. Am. Chem. Soc. (2010)
doi: 10.1021/ja105854m.