Dresden 2014 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 22: Low-Dimensional Systems: Charge Order
TT 22.1: Talk
Monday, March 31, 2014, 15:00–15:15, BEY 81
Competing soft phonon modes in charge-density-wave rare-earth tritellurides — •Michael Maschek1, Sven Krannich1, Frank Weber1, Rolf Heid1, Stephan Rosenkranz2, Ayman Said2, Ian Fisher3, Paula Giraldo-Gallo3, and Ahmet Alatas2 — 1Karlsruhe Institute of Technology, Karlsruhe, Germany — 2Material Science Division, Argonne National Laboratory, Argonne, USA — 3Geballe Laboratory for Advanced Materials, Stanford University, Stanford, USA
We report competing soft phonon modes close to the charge-density-wave (CDW) transition in the rare-earth tritelluride DyTe3 obtained by high energy resolution inelastic x-ray measurements. We investigated transverse polarized modes dispersing along the reciprocal (100) and (001) directions corresponding the two CDW orders lying in the basal plane of the nearly tetragonal unit cell. DyTe3 has two CDW-transitions (TCDW,1=50K, TCDW,2=310K), but for technical reasons we could only investigate the transition at TCDW,2. We found a full softening at qCDW,2=(0,0,0.3) and a strong but not complete softening of the orthogonal mode at qCDW,1=(0.3,0,0) at the same temperature which is reminiscent of previous measurements on TbTe3. Our results are corroborated by lattice dynamical calculations demonstrating the near degeneracy between the two crystallographic axes with respect to the formation of CDW order.