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arXiv · 1410.7592

Wave vector dependent electron-phonon coupling drives charge-density-wave formation in TbTe3

M. Maschek·S. Rosenkranz·R. Heid·A. H. Said·P. Giraldo-Gallo·I. R. Fisher·F. Weber
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Abstract

We present a high energy-resolution inelastic x-ray scattering investigation of the soft phonon mode in the charge-density-wave system TbTe$_3$. We analyze our data based on lattice dynamical calculations using density-functional-perturbation-theory and find clear evidence that strongly momentum dependent electron-phonon-coupling defines the periodicity of the CDW superstructure: Our experiment reveals strong phonon softening and increased phonon line widths over a large part in reciprocal space adjacent to the CDW ordering vector $q_{CDW} = (0, 0, 0.3)$. Further, $q_{CDW}$ is clearly offset from the wave vector of (weak) Fermi surface nesting $q_{FS} = (0, 0, 0.25)$ and our detailed analysis indicates that electron-phonon-coupling is responsible for this shift. Hence, we can add TbTe$_3$, which was previously considered as a canonical CDW compound following the Peierls scenario, to the list of distinct charge-density-wave materials characterized by momentum dependent electron-phonon coupling.

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M. Maschek, S. Rosenkranz, R. Heid, A. H. Said, P. Giraldo-Gallo, I. R. Fisher, F. Weber. 2015-06-29. Wave vector dependent electron-phonon coupling drives charge-density-wave formation in TbTe3. https://doi.org/10.1103/physrevb.91.235146

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