Defects and CDW Pinning in Zr0.95Hf0.05Te_₃

ZrTe₃ is a charge density wave (CDW) compound which exhibits unique properties including both one-dimensional and two-dimensional structural and characteristics and at least two distinct quantum phases. ZrTe₃ enters a unidirectional CDW state below 63 K and a superconducting state below 2 K. The origin of the CDW is believed to be driven by Fermi surface nesting, caused by the one-dimensional nature of ZrTe₃, with long Te-Te chains parallel to the a crystal axis.

Our work focuses on studying the origin of observed defects in Hf-doped ZrTe₃ and their correlation with the unidirectional CDW phase. Using scanning tunneling microscopy, we obtain high-resolution topographies that clearly reveal distinguishable crystal defects. We employ density functional theory (DFT) to simulate the charge density of both the occupied and unoccupied states of the material, aiding in the explanation of each defect's origin. Additionally, we calculate the cross-correlation between individual defects and the CDW maxima, both below and above the CDW transition, demonstrating a clear pinning effect of the CDW by defects as the temperature increases.