Equilibrium and non-equilibrium properties of the charge density wave condensate in quasi-one dimensional conductors

点击翻译按钮获取中文摘要

The proposed project aims at the understanding of the properties of the charge density wave (CDW) condensate in quasi-one dimensional conductors unter equilibrium and non-equilibrium conditions. The equilibrium properties will be studied by reflectivity measurements on single crystals from the microwave to the infrared/visible spectral range (2 cm -1-30000 cm-1), supplemented by dc-transport experiments. We are in particular interested in the low-frequency (i.e. microwave to far-infrared) range where the collective excitations of the CDW-condensate are observed. The influence of the sample quality and doping on the collective CDW-mode will be studied in a systematic way. We are furthermore interested in the effects of normal, i.e. uncondensed electrons on the collective CDW-mode, like screening and damping effects; these effects will be probed by measuring the reflectivity with a dc-electric field applied. The second main issue of the project is the study of the non-equlilibrium properties of the condensed CDW-state using time-resolved techniques: By optical pumping one can create a highly coherent condensed CDW-state. We plan to characterize this induced state by time-domain terahertz spectroscopy in the range 1 - 100 cm-1. We furthermor want to study the influence of single electrons on the amplitude mode of the CDW-using the pump-probe technique: By selective time-domain Raman-scattering one can coherently excite this mode and study its decay while a dc-electric field is applied.