Observation of three types of NDR in flexible VOx Mott memristors

In this study, the negative differential resistance (NDR) phenomenon in a flexible VOx Mott memristor has been investigated. Our findings indicate that these memristors can exhibit three NDR phenomena depending on the compliance current conditions. Specifically, under low compliance current, the memristors are forming-free and display a continuous “S-type” NDR1 characteristic. When subjected to high compliance currents, electrical forming occurs, leading to a Mott phase transition and the subsequent emergence of both S-type NDR2 and “snap-back” NDR. Furthermore, while forming-free devices produce stable NDR1, they are unable to generate stable oscillation pulses due to the lack of a fixed low resistance. In contrast, devices that have undergone the forming process can generate stable oscillating pulses with good threshold switching stability exceeding 107 times.