Phonons in slow motion: Dispersion relations in ultrathin Si membranes

J. Cuffe, E. Chavez, Andrey Shchepetov, P.-O. Chapuis, E.H. El Boudouti, F. Alzina, T. Kehoe, J. Gomis-Bresco, D. Dudek, Y. Pennec, B. Djafari-Rouhani, Mika Prunnila, Jouni Ahopelto, C.M. Sotomayor Torres (Corresponding Author)