ELECTRONIC-PROPERTIES OF ZRTE3

We present the results of a combined experimental and theoretical stud y of the electronic structure of ZrTe3. ZrTe3 is a material that under goes a transition to a charge density wave state at 63 K and displays superconductivity below 2 K. The results of photoemission measurements using synchrotron radiation as well as temperature dependent resistiv ity and thermopower data allow one to sketch a detailed experimental p icture of the electronic structure at the Fermi level. High level TB-L MTO-ASA band structure calculations are used to analyze the bonding si tuation in ZrTe3 and to relate the physical properties of the crystal to the electronic structure. ZrTe3 is a layered material whose structu re is built up from trigonal prismatic ZrTe3 chains with extensive Te- Te interactions perpendicular to the chain direction. These Te-Te inte ractions lead to wide bands in the direction perpendicular to the chai ns of trigonal prisms. Frozen phonon calculations indicate that the de nsity of states at the Fermi level and the shape of the Fermi surface are strongly dependent on the Te-Te interprism interactions. The compl ete computed Fermi surface consists of three independent envelopes: tw o sheet-like surfaces which are associated with the atoms of the Te, g roup and a cylindrical section, the former one being responsible for t he observed charge density wave properties of ZrTe3. The experimental and calculated nesting vectors for the charge density wave are in exce llent agreement. A comparison of the band structures of ZrTe3 with tho se of the isostructural HfTe3 and ThTe3 reveals that HfTe3 should exhi bit similar electronic properties as ZrTe3, whereas ThTe3 should be se mimetallic. Based on the results of the frozen phonon calculations, we predict a strong pressure dependence of the physical properties of Zr Te3 and HfTe3.