Plastic deformation in nanometer scale contacts

The combination of scanning force and tunneling microscopy techniques has made possible the study of plastic deformation in the nanometer scale with unprecedented detail.(1) Retraction of the tip after indentation produces a connective neck which deforms in alternating elastic and yielding stages, in agreement with the theoretical predictions using molecular dynamics simulations. A description of the plastic deformation process in terms of a simple model based on continuum contact mechanics makes possible a quantitative analysis of the experimental results and underlines the connection with the bulk properties of the material.