  Since the demonstration of super-low friction (superlubricity) in graphite at
nanoscale, one of the main challenges in the field of nano- and micro-mechanics
was to scale this phenomenon up. A key question to be addressed is to what
extent superlubricity could persist, and what mechanisms could lead to its
failure. Here, using an edge-driven Frenkel-Kontorova model, we establish a
connection between the critical length above which superlubricity disappears
and both intrinsic material properties and experimental parameters. A striking
boost in dissipated energy with chain length emerges abruptly due to a
high-friction stick-slip mechanism caused by deformation of the slider leading
to a local commensuration with the substrate lattice. We derived a
parameter-free analytical model for the critical length that is in excellent
agreement with our numerical simulations. Our results provide a new perspective
on friction and nano-manipulation and can serve as a theoretical basis for
designing nano-devices with super-low friction, such as carbon nanotubes.
