08 Fakultät Mathematik und Physik

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Institute: search.filters.UBSInstitut.Sonstige EinrichtungAuthor: search.filters.author.Dressel, Martin

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    Field- and frequency dependent transport in the two-dimensional organic conductor α-(BEDT-TTF)2I3
    (1994) Dressel, Martin; Grüner, George; Pouget, Jean-Paul; Breining, Angela; Schweitzer, Dieter
    We studied the electrodynamic response of α-(BEDT-TTF)2I3 in a wide range of frequency, covering microwave and millimeter wave frequencies as well as the optical spectral range, and found a frequency dependent conductivity up to 1000 cm-1 in the low temperature phase. This is accompanied be a non-linear transport with a smooth onset at about 10 V /cm. Our X-ray studies show no indication of superstructure reflections and clearly rule out the formation of a charge density wave ground state. The lack of a temperature dependence in the millimeter wave conductivity between 20 K and 100 K makes hopping transport unlikely.
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    Microwave hall mobility and conductivity in crystals of various (BEDT-TTF) radical salts
    (1991) Dressel, Martin; Helberg, Hans Wilhelm; Schweitzer, Dieter
    We report investigations of the microwave transport properties carried out on the organic conductors and superconductors of (BEDT-TTF)-salts: α-, αt- and β-(BEDT-TTF)2I3, α-(BEDT-TTF)3(NO3)2 and x-(BEDT-TTF)2Cu(NCS)2. The anisotropy and temperature dependence (300 K to 4 K) of the high-frequency conductivity was measured in a microwave cavity at 10.3 GHz. There is low anisotropy in the high conducting plane of the quasi two-dimensional crystals of the (BEDT-TTF)-family, e.g. the (a,b)-plane in β-(BEDT-TTF)2I3; perpendicular to this the microwave conductivity is one order of magnitude lower. At room temperature the microwave Hall mobility at 9.5 GHz of the different phases of (BEDT-TTF)2I3 and (BEDT-TTF)3(NO3)2 is 100 to 200 cm2/Vs in the high conducting planes of the crystals.