Anisotropy of conductivity in rare-earth tritellurides in the static and sliding states of the CDW

We show that the isotropic conductivity in the normal state of rare-earth tritelluride RTe3 compounds is broken by the occurrence of the unidirectional charge density wave (CDW) in the (a,c) plane below the Peierls transition temperature. In contrast with quasi-one-dimensional systems, the resistivity anomaly associated with the CDW transition is strong in the direction perpendicular to the CDW wave vector Q (a-axis) and very weak in the CDW wave vector Q direction (c-axis). We qualitatively explain this result by calculating the electrical conductivity for the electron dispersion with momentum-dependent CDW gap as determined by angle-resolved photoemission spectroscopy (ARPES). Nonlinear transport properties in TbTe3 and GdTe3 have been studied along different crystallographic orientations. The pronounced effect of collective CDW motion is observed along c-axis and is absent completely in the perpendicular direction demonstrating the unidirectional character of the CDW. The threshold electric field for CDW sliding is linearly temperature dependent in a wide range of temperature.