Berlin 2012 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 22: Correlated Electrons: Low-dimensional Systems - Materials 1
TT 22.11: Vortrag
Mittwoch, 28. März 2012, 12:15–12:30, H 0104
Phonon Instability in the CDW Systems 2H-NbSe2 and TiSe2 — •Roland Hott1, Rolf Heid1, Klaus-Peter Bohnen1, Frank Weber1,2, Stephan Rosenkranz2, John-Paul Castellan2, Raymond Osborn2, Goran Karapetrov2, Takeshi Egami3, Ayman Said4, and Dmitry Reznik1,5 — 1Karlsruhe Institute of Technology, Institute of Solid State Physics, P. O. Box. 3640, D-76021 Karlsruhe, Germany — 2Materials Science Division, Argonne National Laboratory, Argonne, Illinois, 60439, USA — 3Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee, 37996, USA — 4Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois, 60439, USA — 5Department of Physics, University of Colorado at Boulder, Boulder, Colorado, 80309, USA
Further investigations on the soft-mode behaviour of phonons in the Charge Density Wave (CDW) systems 2H-NbSe2 and TiSe2 have been performed both theoretically in Density Functional Theory (DFT) based on ab-initio phonon calculations as well as experimentally by means of high resolution Inelastic X-ray Scattering (IXS). For both materials, the theoretical predictions for the phonon softening coincide with the experimentally observed CDW instability behaviour. For 2H-NbSe2 the wave vector dependence of the electron-phonon coupling drives the CDW formation and determines its periodicity [1]. For TiSe2, electron-phonon-coupling is strong enough to stabilize the structural phase transition at finite temperatures [2].
F. Weber et al., Phys. Rev. Lett. 107, 107403 (2011).
F. Weber et al., Phys. Rev. Lett. 107, 266401 (2011).