We found two extra phonon modes in moiré materials that act like sound waves (on top of the usual three sound waves in regular crystals). These are called phasons, a term first used for quasicrystals back in the 1980s. Turns out, phasons are everywhere in these systems! Check out the animation above to see one of these phason modes in action. More technical details: Phys. Rev. Research. 

We showed that when phasons are thermally activated, they can make electrons and excitons "surf." One clear sign of this surfing is how excitons spread out in space and time. Take a look at the animation above to see exciton surfing in action! You can find our theory predictions in Nano Lett. and the experimental confirmation in ACS Nano. Our work has been featured in news coverage by Phys.org, SciTech Daily, EurekAlert!, and other outlets.