Fig. 3
The schematic drawings (a, b) and corresponding potential energy profiles (c, d) of the Au/BTO/NSTO structures for the low- and high-resistance states. In BTO, the red arrows denote the polarization directions, and the “plus” and “minus” symbols represent positive and negative ferroelectric bound charges, respectively. The “circled plus” symbols represent the ionized oxygen vacancies. The blue arrows show the direction of oxygen vacancies drifting across the BTO/NSTO interface