The Atomic-Scale Hysteresis in Non Contact Atomic Force Microscopy

In this research, the hysteresis in the tip-sample interaction force in noncontact force microscopy (NC-AFM) is measured with the aid of atomistic dynamics simulations. The observed hystersis in the interaction force and displacement of the system atoms leads to the loss of energy during imaging of the sample surface. Using molecular dynamics simulations it is shown that the mechanism of the energy dissipation occurs due to bistabilities caused by atomic jumps of the surface and tip atoms in the contact region. The conducted simulations demonstrate that when a gold coated nano probe is brought close to the Au (001) surface, the tip apex atom jumps to the surface; and instantaneously, four surface atoms jump away from the surface toward the tip apex atom. Along this line, particular attention is dedicated to the dependency of the energy loss to different parameters such as the environment temperature, the tip orientation, the surface plane direction, the system size, the distance of the closest approach and the tip oscillation frequency.