Anomalous force dependence of AFM corrugation height of a graphite surface in air

To investigate the force dependence of the AFM corrugation height of graphite under strong repulsive force, we measured the AFM corrugation height and tunneling current between the W lever and graphite surface simultaneously as a function of repulsive force up to ∼1.5×10 -5 N. As a result, we found a peak of the AFM corrugation height at ∼1.1×10 -5 N where the tunneling current showed a sudden increase. Even after the sudden increase of the tunneling current, we could observe atomically resolved AFM/PCM (point contact microscope) images simultaneously.