Nodal rings and drumhead surface states in phononic crystals

• Published in: Nature communications Vol. 10; no. 1; pp. 1769 - 6
• Main Authors: Deng, Weiyin, Lu, Jiuyang, Li, Feng, Huang, Xueqin, Yan, Mou, Ma, Jiahong, Liu, Zhengyou
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 16-04-2019; Nature Publishing Group; Nature Portfolio
• Subjects: 639/766/119/2792; 639/766/25/3927; Acoustic properties; Acoustics; Crystals; Dispersions; Eigenvalues; Fabrication; Humanities and Social Sciences; multidisciplinary; Physics; Rings (mathematics); Science; Science (multidisciplinary); Symmetry; Topology
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-019-09820-8

Three-dimensional topological nodal lines, the touching curves of two bands in momentum space, which give rise to drumhead surface states, provide an opportunity to explore a variety of exotic phenomena. However, solid evidence for a flat drumhead surface state remains elusive. In this paper, we report a realization of three-dimensional nodal line dispersions and drumhead surface states in phononic crystal. Profiting from its macroscopic nature, the phononic crystal permits a flexible and accurate fabrication for materials with ring-like nodal lines and drumhead surface states. Phononic nodal rings of the lowest two bands and, more importantly, topological drumhead surface states are unambiguously demonstrated. Our system provides an ideal platform to explore the intriguing properties of acoustic waves endowed with extraordinary dispersions.
3D topological nodal lines that give rise to drumhead surface states could help study a range of exotic topological phenomena. Here, Deng et al. experimentally demonstrate 3D nodal ring dispersion and topological drumhead surface states for acoustic waves in a phononic crystal.