Mutual Identification between the Pressure-Induced Superlubricity and the Image Contrast Inversion of Carbon...

Previous studies predict pressure-induced superlubricity, but that is still undetermined due to the absence of a probing technique. Here, we present unprecedented mutual identification between the superlubricity and atomic-scale image from atomic force microscopy (AFM) measurement by the first-principles simulation of metallic Cu tip scanning on carbon nanostructures. With decreasing tip height, the sliding potential evolves from anticorrugated, to substantially flattened, and eventually to corrugated patterns, inducing superlubricity of the flattened potential at the critical height. Correspondingly, both the normal forces and the contrast of atomic image patterns also undergo similar inversions at the respective critical tip heights, in accordance with recent experimental observation. On the basis of the underlying mechanism elucidated, the mutual identification between the image contrast inversion and the superlubricity is confirmed. This may advance AFM technology to stimulate the experimental observation of superlubricity from its theoretical studies and may thus promote the development of theory systems of superlubticity.