The role of tip size and orientation, tip-surface relaxations and surface impurities in simultaneous AFM and STM studies on the TiO2(110) surface

In this work we investigate some of the key factors in simultaneously recorded scanning tunneling microscopy (STM) and non-contact atomic force microscopy (nc-AFM) images of the TiO(2)(110) surface, particularly the role of tip size and orientation in the obtained contrast pattern, and the importance of tip-surface relaxations and surface impurities in measured currents. We show that, while using multi-channel scanning modes provides an increase in physical data from a given measurement and greatly aids in interpretation, it also demands much greater rigor in simulations to provide a complete comparison.