Knitting topological bands in artificial sonic semimetals

Frontier investigations on a contemporary family of materials comprise new class topological that have been discovered in three dimensional (3D) semimetallic crystals. Beyond already unconventional quasiparticles Dirac and Weyl semimetals, nodal-line semimetals provide an even richer platform encompassing robust band-touching manifolds exotic transport properties. Classical configurations including artificial crystals emerged as popular systems not only to replicate these properties wave-based scenarios, but particularly also ease experimental complexities electronic permit tuning via variable geometrical designs. Sonic are one such example, which dissimilar fluid or rigid inclusions channels combined tailor the acoustic material response at will. Here, we design cubic lattice guiding allowing us map characteristics quasi-particles excitations audible sound Simply by varying cross section channels, bring forward multiple phase transitions among four different interlaced nodal features, resemble knitting 3D Bloch-bulk bands momentum space. One attribute appears feature version directional massless fermions, is experimentally characterized displays linear crossing direction flat perpendicular one, enabling strongly focused collimated beams, thanks this peculiar dispersion.