J. Phys. IV France
Volume 114, April 2004
Page(s) 305 - 307

J. Phys. IV France
114 (2004) 305
DOI: 10.1051/jp4:2004114066

A comparative mid-infrared study of superconductor BETS 4Hg 2.84Br 8 and metal BETS 4Hg 3Cl 8

N. Drichko1, B. Petrov1, V.N. Semkin1, R.M. Vlasova1, O.A. Bogdanova2, E.I. Zhilyaeva2, R.N. Lyubovskaya2, I. Olejniczak3, H. Kobayashi4 and A. Kobayashi5

1  Ioffe Physico-Technical Institute RAS, 194021 St. Petersburg, Russia
2  Institute of Problems of Chemical Physics, RAS, 142432 Chernogolovka, MD, Russia
3  Institute of Molecular Physics PAS, Poznan, Poland
4  Institute for Molecular Science, Okazaki, 444, Japan Spectrochemical Centre, Japan
5  University of Tokyo Hongo, Bunkyo-ku, Tokyo 113-0033, Japan

Polarized reflectivity spectra of the 2 K organic superconductor BETS 4Hg 2.84Br 8 (T c=2 K) and the metal down to 35 K BETS 4Hg 3Cl 8 were measured in the 700-6000 cm -1 frequency range down to 10 K. Higher anysotropy of reflectivity in the conducting plane of these compounds compared to their BEDT-TTF-based analogues is explained by the differences in intermolecular overlap. No Drude-peak is observed in the optical conductivity spectra of these compounds in the measured frequency range down to 10 K. In BETS 4Hg 3Cl 8 a simultaneous splitting of the electronic mid-infrared band and EMV-coupled $\nu _{3}$(a g) vibration at about 150 K might suggest that the charge-ordering takes place in this compound below 150 K. Key words. organic conductors, infrared spectroscopy.

© EDP Sciences 2004