Temperature-Dependent Studies of Charge Density Wave States in TbTe$_{\mathrm{3}}$

We use temperature-dependent scanning tunneling microscopy (STM) to study charge density wave (CDW) states in TbTe$_{\mathrm{3}}$. TbTe$_{\mathrm{3}}$ undergoes a bulk CDW transition near 335 K, though x-ray data shows evidence for CDW fluctuations up to 363 K.[1] Our STM measurements characterize the well-established, long-range, unidirectional CDW state (q$_{\mathrm{cdw}}$ $=$ 0.71 c*) at 300 K. Our temperature-dependent measurements above T$_{\mathrm{CDW}}$ show evidence for localized static CDW order which is consistent with x-ray detection of CDW fluctuations above T$_{\mathrm{CDW}}$. Surprisingly, we also find evidence for localized static order associated with a second CDW along the a-axis, a CDW state which never establishes long-range coherence in the bulk of TbTe$_{\mathrm{3}}$ even at low temperatures. [1] Ru et al., PRB 77, 035114 (2008).