open access

https://hdl.handle.net/2115/45253

Low-frequency dynamics of κ-(BEDT-TTF)2Cu(NCS)2 observed by 13C NMR

英語

2011-04-01

American Physical Society

Physical Review B

83(14)

144505

κ-(BEDT-TTF)2Cu(NCS)2 [BEDT-TTF: bis-(ethylenedithio)-tetrathiafulvalene] behaves as a semiconductor at high temperatures, whereas it behaves as a Fermi liquid just above the superconducting transition temperature. To reveal the cause of this behavior, we experimented on κ-(BEDT-TTF)2Cu(NCS)2, in which one side of the central C=C in the BEDT-TTF molecules is substituted with 13C nuclei. We perfomed 13C-nuclear magnetic resonance (NMR) spectroscopy on this salt and measured the temperature dependence of its spectral linewidths and its spin-spin relaxation time T2. We found anomalies in its linewidths and T2, which we connected to the ethylene motion within the salt. Compared with the 13C-NMR measurements of κ-(BEDT-TTF-d8)2Cu(NCS)2, we obtained the experimental evidence of the connection between the ethylene motion and the conduction electrons. Considering this connection, we examined the semiconductive behavior of κ-(BEDT-TTF)2Cu(NCS)2 at high temperatures. The contribution of ethylene motion to the electronic state is thought to be a common feature of BEDT-TTF salts.

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©2011 American Physical Society

1098-0121