Fluctuation in Two-Dimensional Stick-Slip Phenomenon Observed with Two-Dimensional Frictional Force Microscope

We used an atomic force microscope combined with a lateral force microscope (AFM/LFM) as a two-dimensional frictional force microscope (2D-FFM) to investigate the two-dimensional behavior of the atomic-scale friction between the cleaved surface of MoS 2 and the Si 3 N 4 tip apex of the microcantilever based on the two-dimensional stick-slip model. As a result, for the scan direction along the row of the stick-points, we found the unstable state where the tip apex shows fluctuation between two adjacent rows of stick-points. On the other hand, near the row of the stick-points, we also found the stable state where the tip apex takes a straight walk on a row of the stick-points without fluctuation.