STM Studies of TbTe3: Evidence for a fully Incommensurate Charge Density Wave

TL;DR

This study uses scanning tunneling microscopy to investigate the charge density wave in TbTe3, revealing a fully incommensurate unidirectional CDW with specific wave-vector characteristics and layer effects.

Contribution

First direct STM observation confirming the incommensurate nature of the charge density wave in TbTe3 with detailed wave-vector analysis.

Findings

Charge density wave is unidirectional and incommensurate.

Wave-vector q_{CDW} is approximately 0.71 * 2π/c.

Layer below shows unit cell doubling effects.

Abstract

We observe unidirectional charge density wave ordering on the cleaved surface of TbTe3 with a Scanning Tunneling Microscope at ~6 K. The modulation wave-vector q_{CDW} as determined by Fourier analysis is 0.71 +/- 0.02 * 2 pi/c. (Where c is one edge of the in-plane 3D unit cell.) Images at different tip-sample voltages show the unit cell doubling effects of dimerization and the layer below. Our results agree with bulk X-ray measurements, with the addition of ~(1/3) * 2 pi/a ordering perpendicular to the CDW. Our analysis indicates that the CDW is incommensurate.