Regensburg 2007 – scientific programme

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O: Fachverband Oberflächenphysik

O 44: Poster Session II (Semiconductors; Oxides and Insulators: Adsorption, Clean Surfaces, Epitaxy and Growth; Surface Chemical Reactions and Heterogeneous Catalysis; Surface or Interface Magnetism; Solid-Liquid Interfaces; Organic, Polymeric, Biomolecular Films; Particles and Clusters; Methods: Atomic and Electronic Structure; Time-resolved Spectroscopies)

O 44.41: Poster

Wednesday, March 28, 2007, 17:00–19:30, Poster C

Fermi surface map of metallic MoTe₂ — •Thorsten Zandt, Robert Heimburger, Christoph Janowitz, and Recardo Manzke — Institut für Physik, Humboldt-Universität zu Berlin, Newtonstraße 15, 12489 Berlin

MoTe₂ undergoes a phase transition at about 1125 K from a low-temperature semiconducting α-phase (hexagonal, isostructural with MoS₂) to a high-temperature metallic β-phase (monoclinic, distorted CdI₂). Upon further cooling an additional phase transition is observed at 250 K for monoclinic β-MoTe₂. This transition is accompanied by a discontinuous structural change, i.e. the monoclinic angle β of 93^∘55″ changes to 90^∘ [1] resulting in an orthorhombic Td-MoTe₂ structure, which is isostructural with WTe₂.

Angular resolved photoemission was performed on β- and Td-MoTe₂ with HeI radiation and in the photon energy range 50eV<hv<100eV at the U125-2 SGM monochromator at BESSY II. Fermi surface images were obtained by scanning the polar emission angle as well as the photon energy while monitoring the photoemission intensity at the Fermi level. The experimental results will be compared with additional tight-binding band structure calculations.

[1] R. Clarke, E. Marseglia and H.P. Hughes, Phil. Mag. B38 121 (1978)