2018/11/20 by Yuanjun Jin, Rui Wang, Hu Xu · 83 citations
Chemistry · Materials Science · Physics and Astronomy · #2D Materials and Applications #Berry #Chemistry #Condensed matter physics #Crystallography #Dirac (video compression format) #Geometric phase #Graphene research and applications #Hexagonal crystal system #Materials science #Phase (matter) #Phonon #Physics #Quantum mechanics #Topological Materials and Phenomena #cond-mat.mes-hall #cond-mat.mtrl-sci
paper · pdf · doi:10.1021/acs.nanolett.8b03492
published in Nano Letters 18(12), 7755-7760 (American Chemical Society) · 16 pages, 4 figures
openalex publication_date 2018/11/20 · arxiv created 2018/11/23 · arxiv updated 2018/11/26 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
The topological quantum states in two-dimensional (2D) materials are fascinating subjects of research, which usually highlight electron-related systems. In this work, we present a recipe that leads to Dirac phonon states with a quantized valley Berry phase in 2D hexagonal lattices by first-principles calculations. We show that candidates possessing the 3-fold rotational symmetry at the corners of the hexagonal Brillouin zone host valley Dirac phonons, which are guaranteed to remain intact with respect to perturbations. We identify that such special topological features populated by Dirac phonons can be realized in various 2D materials. In particular, the monolayer CrI 3, an attractive 2D magnetic semiconductor with exotic applications in spintronics, is an ideal platform to investigate nontrivial phonons in experiments. We further confirm that the phonon Berry phase is quantized to ± π at two inequivalent valleys. The phonon edge states terminated at the projection of phonon Dirac cones are clearly visible. This work demonstrates that 2D hexagonal lattices with attractive valley Dirac phonons will extend the knowledge of valley physics, providing wide applications of topological phonons.