Absence of in-gap modes in charge density wave edge dislocations of the Weyl semimetal (TaSe4)2I

Axion electrodynamics in condensed matter could emerge from the formation of charge density waves (CDWs) in Weyl semimetals. (TaSe4)2I was proposed to be the first material platform for realizing axionic CDW that may host topological defects with one-dimensional in-gap modes. The real-space modulation of the CDW phase and the existence of in-gap modes remain elusive. Here, we present a comprehensive scanning tunneling microscopic and spectroscopic study of a CDW on a (TaSe4)2I (110) surface. The tunneling spectroscopic measurements reveal a CDW gap of similar to 200 meV, in good agreement with prior studies, while the spectroscopy of CDW edge dislocation shows no indication of in-gap states. The bias-dependent scanning tunneling microscopy images indicate that the CDW in (TaSe4)2I is dominated by a large periodic lattice distortion instead of charge modulation, suggesting a non-Peierls mechanism of the CDW instability.

Automated summary

The study on CDW in (TaSe4)2I material reveals a CDW gap of about 200 meV and shows no indication of in-gap states in the spectroscopy of CDW edge dislocation. The CDW in (TaSe4)2I is dominated by a large periodic lattice distortion instead of charge modulation.