A multistate nonvolatile memory operated at sublithographic scale has been strongly desired since other nonvolatile memories have confronted the fundamental size limits owing to their working principles. Resistive switching (RS) in metal-oxide-metal junctions, so-called ReRAM, is promising for next generation high-density nonvolatile memory. Self-assembled oxide nanowire-based RS offers an attractive solution not only to reduce the device size beyond the limitation of current lithographic length scales but also to extract the underlying nanoscale RS mechanisms. Here we demonstrate the multistate bipolar RS of a single Co(3)O(4) nanowire (10 nm scale) with the endurance up to 10(8). In addition, we succeeded to extract a voltage-induced nanoscale RS mechanism rather than current-induced RS. These findings would open up opportunities to explore not only for the intrinsic nanoscale RS mechanisms with the ultimate size limit but also for next generation multistate three-dimensional ReRAM.

We have demonstrated the nonvolatile bipolar resistive memory switching in single crystalline NiO heterostructured nanowires for the first time. The self-assembled NiO nanowires are expected to open up opportunities to explore not only the detailed nanoscale mechanisms in NiO resistive memory switching but also next-generation nanoscale nonvolatile memory devices with the potential for high-density device integration and improved memory characteristics.

We have demonstrated the construction of highly stable resistive switching (RS) junctions with a metal/NiO nanowire/metal structure and used them to elucidate the crucial role of redox events in the nanoscale bipolar RS. The presented approaches utilizing oxide nanowire/metal junctions offer an important system and platform for investigating nanoscale RS mechanisms of various oxide materials.