J. Phys. IV France 114 (2004) 137
Enhanced dielectric response in (BEDT-TTF) (ClMeTCNQ) at the neutral-ionic phase transitionsY. Takahashi1, T. Hasegawa2, T. Akutagawa3 and T. Nakamura3
1 Graduate School of Environmental Earth Science, Hokkaido University, Sapporo 060-0812, Japan
2 Correlated Electron Research Center, AIST, Tsukuba 305-8562, Japan
3 Research Institute for Electronic Science, Hokkaido University, Sapporo 060-0812, Japan
We have studied dielectric properties of (BEDT-TTF)(ClMeTCNQ) around the neutral-ionic (NI) transitions, whose critical temperatures can be tuned from 300 K to 0 K by variation of pressure in the range between GPa. We found that thermal-activation-type dielectric response becomes predominant around the transitions higher than 50 K, while Curie-Weiss type enhancement was not detected above the transitions. Here we feature the dielectric properties in the range above 50 K, so as to contrast another type of dielectrical enhancement observed around the quantum critical point of the NI valence instabilities in (BEDT-TTF)(ClMeTCNQ). Key words. charge-transfer complex - neutral-ionic phase transition - dielectric properties.
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