Artificial synapses based on Josephson junctions with Fe nanoclusters in the amorphous Ge barrier

We have measured the synaptic properties of a magnetic Josephson junction (MJJ) consisting of a barrier of amorphous Ge containing size-selected Fe nanoclusters between two Nb electrodes. We show that the critical current of the device varies with the magnetic order of the clusters and that the magnetic order can be tuned in a quasi-analog way with short electrical pulses of 16 pJ applied through the device. This is the first demonstration of critical current tuning via magnetic order in a nano-clustered MJJ in a material system other than SiMn. This result eliminates the need for a postdeposition annealing step for synaptic MJJs in neuromorphic applications and opens new options to optimize materials, which has the potential to improve the performance of the MJJs and provide a better understanding of the physics of the device.

Automated summary

This study measured the synaptic properties of a magnetic Josephson junction (MJJ) consisting of size-selected Fe nanoclusters in an amorphous Ge barrier between two Nb electrodes. The critical current of the device was found to vary with the magnetic order of the clusters and could be tuned using short electrical pulses. This result is significant as it eliminates the need for postdeposition annealing in synaptic MJJs for neuromorphic applications and opens up possibilities for material optimization and better understanding of the device physics.