Resistive switching is the reversible, non-volatile change in the electrical resistance of a thin insulating or semiconducting layer—sandwiched between two electrodes—in response to the amplitude, polarity, or duration of an applied voltage or current pulse ^[1]. In a typical metal–insulator–metal cell, the initially high-resistance state is converted into a low-resistance set state and subsequently restored to the high-resistance reset state, so that the device retains two distinguishable resistance levels without applied power. The underlying mechanism is redox-based: an applied field drives the drift of mobile oxygen vacancies or cations through the oxide, forming or rupturing a nanoscale conducting filament that short-circuits the insulator. The switching is therefore governed by ion migration rather than by the electronic charge storage used in conventional capacitors ^[2]. Because the resistance state depends on the internal distribution of mobile ionic species, the phenomenon is also described as nanoionic switching and forms the physical basis of memristive behavior, in which the conductance depends on the history of applied charge ^[3].