J. Phys. IV France
Volume 114, April 2004
Page(s) 379 - 381

J. Phys. IV France
114 (2004) 379
DOI: 10.1051/jp4:2004114089

Charge-ordering in $\theta $-(BEDT-TTF) 2MM $^\prime $ (SCN) 4 [ M = Cs, Rb, Tl, M $^\prime $ = Zn, Co]

K. Suzuki1, 1, K. Yamamoto1, M. Uruichi1 and K. Yakushi1

1  The Graduate University for Advanced Studies and Institute for Molecular Science, Nishigonaka, Myodaiji-cho, Okazaki, Aichi, 444-8585, Japan

Vibrational spectra, x-ray scattering and electrical resistivity of $\theta $ -(BEDT-TTF) 2MM $^\prime $(SCN) 4, [ M = Cs, Rb, Tl, M $^\prime $ = Zn, Co] were measured in various temperature ranges. Vibrational spectra with the aid of x-ray scattering manifested charge disproportionation and charge ordering in their low-temperature phases. Except $\theta $ -(BEDT-TTF) 2CsM $^\prime $(SCN) 4, the orthorhombic form provided a horizontal stripe. On the other hand, monoclinic $\theta $-(BEDT-TTF) 2TlZn(SCN) 4 provided a diagonal stripe. The electronic state of the high-temperature phase is discussed based on the line shape of the Raman spectrum. Key words. Charge-ordering, BEDT-TTF, Raman spectroscopy, infrared spectroscopy.

© EDP Sciences 2004