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HL: Fachverband Halbleiterphysik

HL 78: 2D Materials beyond Graphene: Dynamics and Excitation

HL 78.9: Talk

Thursday, March 10, 2016, 12:45–13:00, S054

Investigations on the Phonon Spectrum of TiSe₂ in the CDW Phase — •Roland Hott, Rolf Heid, and Frank Weber — Karlsruhe Institute of Technology, Institute of Solid State Physics, P.O.B. 3640, D-76021 Karlsruhe, Germany

We report recent results of our investigations on the Charge Density Wave (CDW) phase transition in TiSe₂, performed both experimentally by means of high resolution Inelastic X-ray Scattering (IXS) as well as theoretically by Density Functional Theory (DFT) based ab-initio phonon calculations [1].

We extended our calculations to the case of Cu-doping where we found a huge hardening of the CDW-related soft phonon due to strong chemical bonding of the Cu atoms to the TiSe₂ host lattice. Moreover, we investigated the phonon spectrum of TiSe₂ in the CDW phase where we find the expected stabilisation of the lattice. Nevertheless, we still obtain here a sizeable electron-phonon coupling for the phonons which derive from the soft phonons of the normal (CDW-undistorted) phase.
[1] F. Weber, S. Rosenkranz, J.-P. Castellan, R. Osborn,

G. Karapetrov, R. Hott, R. Heid, K.-P. Bohnen, A. Alatas,

PRL 107, 266401 (2011)