Evidence for charge order in organic superconductors obtained by vibrational spectroscopy

✍ Scribed by Natalia Drichko; Stefan Kaiser; Yaxiu Sun; Conrad Clauss; Martin Dressel; Hatsumi Mori; John Schlueter; Elena I. Zhyliaeva; Svetlana A. Torunova; Rimma N. Lyubovskaya

• Publisher: Elsevier Science
• Year: 2009
• Tongue: English
• Weight: 402 KB
• Volume: 404
• Category: Article
• ISSN: 0921-4526
• DOI: 10.1016/j.physb.2008.11.038

✦ Synopsis

We study charge disproportionation in few quasi-two-dimensional BEDT-TTF-based compounds by following the temperature dependence of a charge-sensitive vibration n 27 ðB 1u Þ of BEDT-TTF molecule.

While in a charge ordered insulator y-(BEDT-TTF) 2 RbZn(SCN) 4 a difference between charge on the lattice sites is as high as 0.6e, a small charge disproportionation of 0.15-0.2e is found in two metallic compounds that become superconducting at low temperatures b 00 -(BEDT-TTF) 2 SF 5 CH 2 CF 2 SO 3 and b-(EDT-TTF) 4 ½Hg 3 I 8 ð1ÀxÞ . In contrast to these, a pure metallic b 00 -(BEDT-TTF) 2 SO 3 CHFSF 5 does not show any presence of charge disproportionation. This study suggests a correlation between a slight charge disproportionation in the metallic state and superconductivity.