Fig. 5
From: Mechanical dissipation from charge and spin transitions in oxygen-deficient SrTiO3 surfaces
Electronic transitions in oxygen vacancies caused by the potential of an oscillating AFM tip. a AFM tip, through electrostatic and van der Waals interactions, modifies the electron local potential at the surface in an area with one or several oxygen vacancies, altering their chemical potential (Fermi level) with respect to each other and the surrounding STO. Local alteration of chemical potential and electron level shifting can lead to a realignment of the impurity levels of VO facilitating electron transfer and provoking charge state transitions in the system. Several possible paths thereof are sketched in b where scenario (ii) and (iii) correspond to electron exchange between single vacancy and conduction band of SrTiO3, (v), (vi), (vii)—electron exchange between group of vacancies, and (viii), (ix)—electron exchange between vacancies and surface 2DEG
