Michael Fogler - University of California, San Diego (UCSD) We report on experimental and theoretical studies of 2D van der Waals materials with a very small rotational misalignment, the twisted bilayer graphene (TBG) and twisted hexagonal boron nitride (hBN). The lattice mismatch of the layers in such materials gives rise to a periodic network of dislocations (solitons) with periods as larger as few hundred nanometers. The solitons and their effect on collective modes of the systems are visualized by infrared nano-imaging experiments. In TBG, the solitons are seen to alter propagation of plasmons. We explain this in terms of a strong infrared response of chiral electron states bound to the solitons. In hBN, the solitons are observed to shift and broaden phonon-polariton modes. We interpret this as evidence of local strain effects on the phonon spectra. [1] S.S. Sunku, G.X. Ni, B.Y. Jiang, H. Yoo, A. Sternbach, A.S. McLeod, T. Stauber, L. Xiong, T. Taniguchi, K. Watanabe, P. Kim, M.M. Fogler, D.N. Basov, Photonic crystals for nano-light in moiré graphene superlattices, Science 362, 1153-1156 (2018). [2] G. X. Ni, H. Wang, B.-Y. Jiang, L. X. Chen, Y. Du, Z. Y. Sun, M. D. Goldflam, A. J. Frenzel, X. M. Xie, M. M. Fogler, D. N. Basov, Soliton superlattices in twisted hexagonal boron nitride, Nat. Commun. 10, 4360 (2019).