Incommensurate structural modulation and electronic localization in bis-tetramethyltetraselenafulvalene thiocyanate

We present transport, magnetic and structural properties of bis-tetramethyltetraselenafulvalene thiocyanate [(TMTSeF)2SCN]. At ambient pressure, this compound is very close to the critical pressure above which the metallic state is stabilized over the entire temperature range. Unusual phenomena for the Bechgaard salts are observed in (TMTSeF)2SCN with the formation of a short-range incommensurate modulation below about 90 K, associated with a decrease in the electronic mobility. This decrease may be due to the electronic localization induced by the short-range incommensurate potential created by the modulation. © 1987 The American Physical Society.