Microwave conductivity of the organic charge density wave conductor (fluoranthene)2X
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Zugriff:
We have investigated the temperature dependence of the microwave conductivity of the organic CDW-conductor (FA) 2 X at frequencies of 4.2, 10.2 and 23.5 GHz and compared our data with the d.c. conductivity of these crystals [1]. Down to temperatures of about 80 to 60 K an excellent agreement has been found. In the quasi-metallic high temperature range no frequency dependence of the conductivity is observed. Upon cooling a sharp phase transition already known from d.c. measurements occurs at temperatures T p of 182 to 175 K depending on the counterion X − = PF 6 − , SbF 6 − . At temperatures far below this Peierls transition, however, deviations from d.c. results are observed; while the d.c. conductivity displays thermally activated behaviour the microwave conductivity leads into a plateau and remains almost constant down to 4 K. The onset of this plateau lies at temperatures from 80 to 60 K. At 20 K the microwave conductivity at 10.2 GHz is about 10 orders of magnitude higher than the d.c. values. We interpret these results as a clear signature of the Frohlich mode resulting from the CDW ground state in (FA) 2 X. The agreement of microwave and d.c. data even at temperatures below the Peierls transition can be ascribed to screening of the CDW by thermally excited charge carriers.
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Microwave conductivity of the organic charge density wave conductor (fluoranthene)2X
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Autor/in / Beteiligte Person: | Helberg, H. W. ; Hauenschild, C. ; Riess, W. ; Brütting, Wolfgang ; Schwoerer, Markus |
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Quelle: | Scopus-Elsevier |
Medientyp: | unknown |
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