Tunnel junction based memristors as artificial synapses.

We prepared magnesia, tantalum oxide, and barium titanate based tunnel junction structures and investigated their memristive properties. The low amplitudes of the resistance change in these types of junctions are the major obstacle for their use. Here, we increased the amplitude of the resistance change from 10% up to 100%. Utilizing the memristive properties, we looked into the use of the junction structures as artificial synapses. We observed analogs of long-term potentiation, long-term depression and spike-time dependent plasticity in these simple two terminal devices. Finally, we suggest a possible pathway of these devices toward their integration in neuromorphic systems for storing analog synaptic weights and supporting the implementation of biologically plausible learning mechanisms.

Preparation of Ta-O-based tunnel junctions to obtain artificial synapses based on memristive switching.

Magnetron sputtering and optical lithography are standard techniques to prepare magnetic tunnel junctions with lateral dimensions in the micrometer range. Here we present the materials and techniques to deposit the layer stacks, define the structures, and etch the devices. In the end, we obtain tunnel junction devices exhibiting memristive switching for potential use as artificial synapses.