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. We here demonstrate that the room-temperature phase of (TaSe4)2I is a Weyl semimetal with 24 pairs of Weyl nodes. Owing to its quasi-1D structure, (TaSe4)2I hosts an established CDW instability just below room temperature. Using X-ray diffraction, angle-resolved photoemission spectroscopy, and first-principles calculations, we find that the CDW in (TaSe4)2I couples the bulk Weyl points and opens a band gap. The correlation-driven topological phase transition in (TaSe4)2I 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.
@article{arxiv.1909.04037,
title = {A Charge-Density-Wave Topological Semimetal},
author = {Wujun Shi and Benjamin J. Wieder and H. L. Meyerheim and Yan Sun and Yang Zhang and Yiwei Li and Lei Shen and Yanpeng Qi and Lexian Yang and Jagannath Jena and Peter Werner and Klaus Koepernik and Stuart Parkin and Yulin Chen and Claudia Felser and B. Andrei Bernevig and Zhijun Wang},
journal= {arXiv preprint arXiv:1909.04037},
year = {2021}
}
Comments
Final version, 14 pg main text + 28 pg supplement, 5 + 16 figures