STM Studies of the CDW System TbTe$_3$

We present STM data on the Charge Density Wave (CDW) in the Rare Earth Tri-Telluride TbTe$_3$. Topography scans as large as 250$\times$250 $\AA^2$ were taken with voltage bias as high as 0.8 Volt. Fourier analysis shows an incommensurate unidirectional modulation with wave-vector q $\approx$ 0.71 a*. The topographic scans at different bias voltages are used to highlight the difference in structure of the CDW and lattice period-doubling effects, either from the Te-Te dimerization, or from the Te-Tb layer directly below the surface.