Atomic-Scale Surface Strain and Charge Density Wave States in TbTe₃

In the bulk of TbTe₃, a unidirectional charge density wave (CDW) state is established along the c-crystal axis below ~336 K. Surprisingly, in our recent near-room temperature scanning tunneling microscopy (STM) measurements [1], we detect spatially-separated perpendicular unidirectional CDWs established along both the a- and c-crystal axes with no directional preference for the in-plane crystal axes (a or c). Our measurements indicate that surface strain may play a role in driving the observed CDW orders. Here we present our work on quantifying atomic-scale strain at the surface of TbTe₃. We then discuss connections between surface strain and the locally observed CDW order.

[1] Fu et al., PRB, 94, 205101, 2016.