Author(s): A. R. Khisameeva, D. A. Khudaiberdiev, I. M. Moiseenko, P. A. Gusikhin, A. S. Astrakhantseva, A. Shuvaev, A. Pimenov, D. A. Svintsov, I. V. Kukushkin, and V. M. Muravev We experimentally investigate the terahertz spectrum of plasma excitations in a plasmonic crystal based on AlGaN/GaN two-dimensional electron system (2DES). While screened plasmon modes with linear dispersion are readily observed in such structures, unscreened modes localized in the slots between th… [Phys. Rev. Lett. 137, 046901] Published Mon Jul 20, 2026