(color online) The mechanism of new type RRAM: physical switching. (a), (b) Discovery of the resistive switching effect in the graphene field effect transistor.^[78] (a) Schematic of mechanism and (b) demonstration of resistive switching effect. (c) Mechanism illustration of the physical switching.^[81] The SEM images are the states before/after (up/down) breakdown. (d) The high magnification SEM images after breakdown.^[81] The upper and bottom images show the nanogap and Si nanocrystal, respectively. (e) Nonpolar switching characteristics of the physical switching devices, which indicate that the device is based on the thermal effect.^[90] (f) The relationship of set voltage value and temperature.^[90]