Regensburg 2010 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 11: CE: Low-dimensional Systems - Materials 2

TT 11.2: Vortrag

Dienstag, 23. März 2010, 09:45–10:00, H18

Raman scattering evidence for a cascade-like evolution of the charge-density-wave collective amplitude mode — •Hans-Martin Eiter¹, Michela Lavagnini², Leonardo Tassini¹, Bernhard Muschler¹, Jiun-Haw Chu³, Nancy Ru³, Ian R. Fisher³, Leonardo Degiorgi², and Rudi Hackl¹ — ¹Walther Meissner Institute, Bavarian Academy of Sciences and Humanities, 85748 Garching — ²Laboratorium für Festkörperphysik, ETH - Zürich, CH-8093 Zürich, Switzerland — ³GLAM, Stanford University, CA 94304, USA

We report results of Raman scattering experiments as a function of temperature on the charge-density-wave (CDW) systems DyTe₃ and on LaTe₃ at 6 GPa applied pressure. We clearly identify the unidirectional collective CDW amplitude excitation and follow their temperature dependence in the range from 6 K to 311 K. Surprisingly, we discover that the amplitude mode develops as a succession of two mean-field, BCS-like transitions at two different temperatures.

Tri-tellurides with heavier rare-earth atoms (i.e. Tm, Er, Ho, Dy) undergo another phase transition to a bidirectional CDW at low temperatures. In DyTe₃ we find spectroscopic evidence for the amplitude mode excitation associated with the bidirectional CDW occuring below 50 K.

This work is supported by the DFG under Grant No. Ha2071/5-1.