Vestigial nematic order in Pd-RTe3 studied using X-ray diffraction TEmperature Clustering (X-TEC)

Nematic order can arise from a number of physical origins. A vestigial nematic order associated with a disordered uni-directional charge density wave (CDW) has been a topic of much theoretical interest with the relatively little direct experimental investigation. Here, we use diffuse x-ray scattering to study the effects of Pd-intercalation, which introduces controlled disorder, on CDW formation in ErTe3, a weakly orthorhombic material for which CDW fluctuations are present in both in-plane directions. For this, three-dimensional reciprocal space volumes were collected covering 20000 Brillouin Zones using the Pilatus 2M CdTe detector on Sector 6-ID-D at the Advanced Photon Source. We then use our recently developed machine learning tool, X-TEC [1] to explore these comprehensive data sets.
For the pristine compound, the tool is quickly able to identify the onset of two CDW transitions and the associated order parameters. For the intercalated samples, we explore the evolution of diffuse scattering near the CDW ordering wave vectors as well as the lattice Bragg peaks to study the disorder-driven melting of the CDW.

[1] Venderley et al, https://arxiv.org/abs/2008.03275