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TT: Fachverband Tiefe Temperaturen
TT 3: CE: Charge Density Wave \& Peierls Instability
TT 3.9: Talk
Monday, March 14, 2011, 12:45–13:00, HSZ 304
Raman study of the charge density wave system ErTe3 — •Hans-Martin Eiter1, Michela Lavagnini1, Reinhard Roßner1, Jiun-Haw Chu3, Ian R. Fisher3, Leonardo Degiorgi2, and Rudi Hackl1 — 1Walther-Meissner Institut, Bayerische Akademie der Wissenschaften, 85748 Garching — 2Laboratorium für Festkörperphysik, ETH - Zürich, CH-8093 Zürich, Switzerland — 3GLAM, Stanford University, CA 94304, USA
We present results of Raman scattering experiments on ErTe3 as a function of temperature and photon polarization. At high energy, electron-hole excitations across the charge density wave (CDW) gap are observed. Below 100 cm−1 strongly temperature dependent collective excitations dominate the spectra. With both light polarizations along the c-axis of the single domain crystal a large gap 2Δ0 in the range of 0.4 eV opens below the first CDW transition at 265 K. The gap of the second transition at 155 K is only present for aa polarizations. The related amplitude modes do not exactly mirror the anisotropy of the electronic gaps but rather show components of the the higher tetragonal symmetry highlighting the intimate coupling of the electrons to the quasi-tetragonal lattice. The high gap ratios 2Δ0/kBTc in the range above 10 compare well to results of photoemission experiments and indicate that fluctuations substantially suppress the mean-field transition temperature.
This work is supported by the DFG under Grant No. Ha2071/5.