We experimentally observed atomic-scale torsional stick-slip behavior in individual nanotubes of tungsten disulfide (${\mathrm{WS}}_2$). When an external torque is applied to a ${\mathrm{WS}}_2$ nanotube, all its walls initially stick and twist together, until a critical torsion angle, at which the outer wall slips and twists around the inner walls, further undergoing a series of stick-slip torque oscillations. We present a theoretical model based on density-functional-based tight-binding calculations, which explains the torsional stick-slip behavior in terms of a competition between the effects of the in-plane shear stiffness of the ${\mathrm{WS}}_2$ walls and the interwall friction arising from the atomic corrugation of the interaction between adjacent ${\mathrm{WS}}_2$ walls.

• Received 10 August 2008

DOI:https://doi.org/10.1103/PhysRevLett.101.195501