Abstract
Department of Applied Physics, Faculty of Engineering University of Tokyo
There exist more than 60 kinds of transition metal dichalcogenides which have layered crystal structure, and some of the physical properties exhibit two dimensional character due to this crystal structure. In this paper, the physical properties of the compounds of IVb, Vb and VIb elements with chalcogen elements are reviewed. The crystal structures including polytypes, band structures, optical properties, electrical transport properties, and superconduct-ing properties are explained on the basis of recent experimental and theoretical investigations.
The charge density waves (CDW) transition which occurs in the crystals of Vb element such as IT-TaS2, 2H-NbSe2, is the most distinguished phenomenon in these materials, since it comes from the two dimensional characterof Fermi surface. This transition induces drastic changes in the wide range of physical properties. These are discussed in addition to the physical origin of CDW.
