Figure 4. The oxygen content fluctuation adjusted by applied bias in the “forming” process.

(a), EELS of O-K edge under different voltages at “Interface”. (b), The method used to calculate the intensity ratio for esimating the oxygen concentration. c, The intensity ratio obtained from the EELS data of two positions in Fig. 4 a with the reference data calculated from reference ²⁹ with the same mothed, the red numbers label the stoichiometric values x in SrTiO_x, and the gray arrow indicates the sequence of the experiments.