A charge-density-wave topological semimetal

Topological physics and strong electron-electron correlations in quantum materials are typically studied independently. However, there have been rapid recent developments in quantum materials in which topological phase transitions emerge when the single-particle band structure is modified by strong interactions. Here we demonstrate that the room-temperature phase of (TaSe4)(2)I is a Weyl semimetal with 24 pairs of Weyl nodes. Owing to its quasi-one-dimensional structure, (TaSe4)(2)I also hosts an established charge-density wave instability just below room temperature. We show that the charge-density wave in (TaSe4)(2)I couples the bulk Weyl points and opens a bandgap. The correlation-driven topological phase transition in (TaSe4)(2)I provides a route towards observing condensed-matter realizations of axion electrodynamics in the gapped regime, topological chiral response effects in the semimetallic phase, and represents an avenue for exploring the interplay of correlations and topology in a solid-state material.

Automated summary

The study demonstrates that (TaSe4)(2)I is a Weyl semimetal with 24 pairs of Weyl nodes at room temperature, and also exhibits an established charge-density wave instability. The charge-density wave in (TaSe4)(2)I couples the bulk Weyl points and opens a bandgap, providing a pathway for exploring the interplay of correlations and topology in a solid-state material.