Observation of Higher Order Nodal Line Semimetal in Phononic Crystals

• DOI: 10.48550/arxiv.2401.04502
• Publication Date: 2024-01-01
• Authors: Qiyun Ma; Zhenhang Pu; Liping Ye; Jiuyang Lu; Xueqin Huang; Manzhu Ke; Hailong He; Weiyin Deng; Zhengyou Liu
• Keywords: Surface States; Topological insulator; Line (geometry)

Higher-order topological insulators and semimetals, which generalize the conventional bulk-boundary correspondence, have attracted extensive research interest. Among them, higher-order Weyl semimetals feature two-fold linear crossing points in three-dimensional (3D) momentum space, 2D Fermi-arc surface states, 1D hinge states. nodal-point possessing or Dirac been implemented. However, nodal-line nodal-surface remain to be further explored experiments spite of many previous theoretical efforts. In this work, we realize a second-order semimetal 3D phononic crystals. The bulk nodal lines, drumhead states guaranteed by Zak phases, flat attributed kz-dependent quadrupole moments, are observed simulations experiments. Our findings nondispersive may promote applications acoustic sensing energy harvesting.