2020/03/31 by Jiabin Yu, Zhi-Da Song, Chao-Xing Liu +1 · 6 citations
Materials Science · Mathematics · Physics and Astronomy · #Axion #Condensed matter physics #Gapless playback #Graphene research and applications #Homogeneous space #Mathematics #Particle physics #Physics #Quantum many-body systems #Quantum mechanics #Statistical physics #Theoretical physics #Topological Materials and Phenomena #Topology (electrical circuits) #cond-mat.mes-hall #cond-mat.mtrl-sci
paper · pdf · doi:10.1103/physrevlett.125.036401
published in Physical Review Letters 125(3), 036401 (American Physical Society) · Close to the published version
openalex publication_date 2020/07/17 · arxiv created 2020/07/18 · arxiv updated 2020/07/21 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
Gapless criteria that can efficiently determine whether a crystal is gapless or not are particularly useful for identifying topological semimetals. In this work, we propose a sufficient gapless criterion for three-dimensional noninteracting crystals, based on the simplified expressions for the bulk average value of the static axion field. The brief logic is that two different simplified expressions give the same value in an insulator, and thus the gapless phase can be detected by the mismatch of them. We demonstrate the effectiveness of the gapless criterion in the magnetic systems with space groups 26 and 13, where mirror, glide, and inversion symmetries provide the simplified expressions. In particular, the gapless criterion can identify gapless phases that are missed by the symmetry-representation approach, as illustrated by space group 26. Our proposal serves as a guiding principle for future discovery of topological semimetals.