Numéro
J. Phys. IV France
Volume 03, Numéro C2, Juillet 1993
International Workshop on Electronic Crystals
ECRYS - 93
Page(s) C2-125 - C2-128
DOI http://dx.doi.org/10.1051/jp4:1993224
International Workshop on Electronic Crystals
ECRYS - 93

J. Phys. IV France 03 (1993) C2-125-C2-128

DOI: 10.1051/jp4:1993224

Anomalous features of the CDW transition in metallic 2H dichalcogenides

C. AYACHE1, R. CURRAT2, B. HENNION3 and P. MOLINIE4

1  D.R.F.M.C., SPSMS/LCP, CENG, BP. 85X, 38041 Grenoble cedex, France
2  I.L.L., BP. 156X, 38042 Grenoble cedex, France
3  L.L.B., CEN Saclay, 91191 Gif-sur-Yvette, France
4  I.M.N., CNRS, 44072 Nantes cedex, France


Abstract
The metallic dichalcogenides of transition metals which cystallise in the trigonal prismatic 2H structure, are considered as a model family for the study of charge-density-wave transitions of the metal-metal type. We review different properfies and their evolution in the series : transport, specific heat, rnagnetic susceptibility, soft phonon dynamics. For temperatures higher than the transition temperature, Td many characters underline the departure from the normal metal behaviour as well as from the behaviour resulting from the presence of the simple soft mode predicted by weak-coupling theories. A phenomenological analysis rather suggests for this family a very strong coupling mechanism involving local vibronic pseudo spins, narrow-band character and proximity to an order-disorder transition.



© EDP Sciences 1993