Unexpected speed-dependent friction in graphene

https://phys.org/news/2022-12-unexpected-speed-dependent-friction-graphene.html

"tip of an atomic force microscope is moved across the surface... weak and almost constant frictional force... Above threshold, friction increases with speed of tip... larger the Moiré superstructure the lower the threshold at which friction becomes speed-dependent... greater resistance at ridges of Moiré superstructures during movement of tip... ridges undergo elastic deformation due to pushing tip before relaxing again when pressure sufficiently high... frictional forces increase with speed of  tip"