Unconventional surface responses of fourfold-degenerate Dirac-nodal-line semimetals in sonic crystals

• DOI: 10.1103/physrevapplied.20.064047
• Publication Date: 2023-12-28T15:03:26Z
• Authors: Chang-Yin Ji; Jijie Tang; Xiao-Ping Li; Zheng Tang; Di Zhou; Yeliang Wang; Feng Li; Jiafang Li; Yugui Yao
• Keywords: Brillouin zone; Surface States; Line (geometry)

Three-dimensional nodal-line semimetals (NLSMs) are of remarkable importance for both enriching topological physics and wave management. However, NLSMs realized in acoustic systems twofold band degenerate called Weyl NLSMs. Here, we report on the experimental observation Dirac with fourfold degeneracy sonic crystals. We reveal that properties entirely different than those conventional The Berry phase related to nodal line (DNL) is $2\ensuremath{\pi}$, which results surface responses two radically situations: a torus state occupying entire Brillouin zone (SBZ) one without any SBZ. further arcs caused by DNL can change from open closed contours. findings their unique response may bring about exciting frontiers flexible manipulation waves.