Reversible Tip-induced Structural Modifications in Scanning Tip Microscopy

Abstract

Tip-induced structural modifications of the Si(100) surface in scanning tunneling microscopy (STM) and atomic force microscopy (AFM) are investigated with first-principles total energy pseudopotential calculations. The atoms of the tungsten tip and the surface are fully relaxed according to the tip-surface interactions. At tip-surface distances relevant to STM measurements, the tip is found to significantly influence the dynamics of the surface atoms leading a new understanding of the microscopic STM measurement process. At smaller tip-surface distances, the tip-surface interactions can be used to directly manipulate the geometry of the surface atoms. At very low temperature, the theory predicts the existence of micromechanical hysteresis on an atomic scale which can be measured in low temperature AFM. The theory also leads to the discovery of a specific protocol of tip movements with implications towards a novel design for an ultra-high density memory storage device.