Coexistence Of The Resistance Switching And Magnetoresistance Effect In ZnO-Co Nano-material

The spin memristive devices combining memristance and magnetoresistance have promising applications in multibit nonvolatile data storage and artificial neuronal computing. So it is in significance and difficulty to seek a material, whose resistances can be stably switched at different resistance states modulated by electric field and magnetic field. In this paper, the spin memristive devices, in which ZnO-Co film or ZnO/ZnO-Co one are the storage layer, respectively, were designed and grown by magnetron sputtering. Their resistance switching and magnetoresistance effect were investigated.(1) Pt/ZnO-Co/Pt exhibits a stable bipolar resistance switching behavior without any electroforming process in advance. The phenomena may demonstrate a positive effect from the distributed Co nanoparticles in ZnO-based storage layer, which can serve as conduction precursors and enhance the local electrical field and then correspondingly facilitate the formation of conductive paths, leading to a better switching performance;(2) The Pt/ZnO/ZnO-Co/Pt device, in which the storage layer combines a nanostructured ZnO-Co layer and a ZnO layer, exhibits bipolar resistive switching characteristics, which can be explained by the accumulation of oxygen vacancies due to the migration of oxygen ions by external electrical stimuli and the contribution of Co particles in ZnO-Co layer. Moreover, magnetoresistance effect at room temperature can be further observed in the device at high and low resistance states, respectively. Therefore, by electric and magnetic controlling, four resistance states are achieved in this system.(3) On the basis of the above results, adjusting the concentration of Co in ZnO-Co layer can tune its resistance. As this, four resistance states can be also realized in a Pt/ZnO-Co/Pt device.In conclusion, the devices with a composite ZnO/ZnO-Co storage layer or a single ZnO-Co one show bipolar resistive switching characteristics. Room temperature magnetoresistance effect can be further achieved in the device at high and low resistance states, respectively. Thus, four resistance states can be obtained in the device by the modulation of both electric and magnetic field at room temperature. The results can supply a new clue for the realization of multiple resistance states in a material using an easier and simpler deposition method.