Dresden 2006 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
TT: Tiefe Temperaturen
TT 19: Correlated Electrons: Low-dimensional Materials
TT 19.15: Vortrag
Dienstag, 28. März 2006, 17:45–18:00, HSZ 301
Phase transition of β-MoTe2 studied by transport measurements and soft x-ray photoemission spectroscopy — •Thorsten Zandt, Robert Heimburger, Lenart Dudy, Beate Müller, Alica Krapf, Helmut Dwelk, Christoph Janowitz, and Recardo Manzke — Inst.f.Physik, Humboldt-Universität zu Berlin
MoTe2 undergoes a phase transition at about 1125 K from a low-temperature semiconducting β-phase (hexagonal) to a high-temperature metallic β-phase (monoclinic). Upon cooling, for monoclinic β-MoTe2 an additional phase transition is observed at 250 K. This transition is accompanied by a discontinuous structural change, i.e. the monoclinic angel β of 93∘55′ changes to 90∘ [1] resulting in an orthorhombic Td-MoTe2 structure. In this contribution we present a detailed temperature dependent study of the transport and electronic properties of the 250K-phase transition of the MoTe2 single crystals. The in-plane resistivity as well as the magnetic susceptibility reveal a distinct hysteretic behavior at the phase transition. In addition, temperature dependent soft x-ray photoemission of Te 4d core levels show a large splitting, which could indicate the occurrence of charge density wave (CDW) formation in β-MoTe2, although there is no direct evidence yet like superlattice spots in the electron diffraction pattern. This will be discussed within a model in which the competition between Coulomb and elastic interactions may drive the first-order lock-in transition to Td-MoTe2 at 250 K.
[1] Clarke, R, Marseglia E and Hughes H P 1978 Phil. Mag. 38 121