Regensburg 2007 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 22: Low-dimensional Systems - Materials
TT 22.3: Vortrag
Donnerstag, 29. März 2007, 10:00–10:15, H18
Drude response and evidence of a density-wave state in the β″−(ET)2SF5CH2CF2SO3 organic superconductor — •Stefan Kaiser1, Natalia Drichko1, Martin Dressel1, and John Schlueter2 — 11. Physikalisches Institut, Universität Stuttgart, 70550 Stuttgart, Germany — 2Material Science Division, Argonne National Laboratory, Argonne, Illinois 60439-4831, U.S.A.
The quasi-two-dimensional organic superconductor β″−(ET)2SF5CH2CF2SO3 is a prominent example of highly correlated electron systems. It raises interest because it forms a density-wave state around 140 K proposed by [Nam et al., PRL 87, 117001]. Previous optical measurements do not show a Drude contribution. Here we present reflectance measurements at frequencies down to 10 cm−1 and temperatures down to 1.8 K, well below the superconducting transisition Tc=5.2 K. Already at room temperature a Drude behavior is observed which grows for lower temperatures. For light polarized in the high reflecting direction a pronounced gap opens around 200 cm−1 for T<125 K. This we relate to the density-wave-gap driven by the nesting of the quasi-one-dimensional Fermi surface. The gap shows a slight anisotropy.