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 which topological phase transitions emerge when the single-particle band structure is modified by interactions. We here demonstrate that room-temperature of (TaSe$_4$)$_2$I a Weyl semimetal with 24 pairs nodes. Owing to its quasi-1D structure, hosts an established CDW instability just below room temperature. Using X-ray diffraction, angle-resolved photoemission spectroscopy, first-principles calculations, we find couples bulk points opens gap. The correlation-driven transition provides route towards observing condensed-matter realizations axion electrodynamics gapped regime, chiral response effects semimetallic phase, represents avenue for exploring interplay topology solid-state material.