  The peeling of an immobile adsorbed membrane is a well known problem in
engineering and macroscopic tribology. In the classic setup, picking up at one
extreme and pulling off results in a peeling force that is a decreasing
function of the pickup angle. As one end is lifted, the detachment front
retracts to meet the immobile tail. At the nanoscale, interesting situations
arise with the peeling of graphene nanoribbons (GNRs) on gold, as realized,
e.g., by atomic force microscopy. The nanosized system shows a constant-force
steady peeling regime, where the tip lifting h produces no retraction of the
ribbon detachment point, and just an advancement h of the free tail end. This
is opposite to the classic case, where the detachment point retracts and the
tail end stands still. Here we characterise, by analytical modeling and
numerical simulations, a third, experimentally relevant, setup where the
nanoribbon, albeit structurally lubric, does not have a freely moving tail end,
which is instead elastically tethered. Surprisingly, novel nontrivial scaling
exponents appear that regulate the peeling evolution. As the detachment front
retracts and the tethered tail is stretched, power laws of h characterize the
shrinking of the adhered length the growth of peeling force and the peeling
angle. These exponents precede the final total detachment as a critical point,
where the entire ribbon eventually hangs suspended between the tip and
tethering spring. These analytical predictions are confirmed by realistic MD
simulations, retaining the full atomistic description, also confirming their
survival at finite experimental temperatures.
