  Continued progress in high speed computing depends on breakthroughs in both
materials synthesis and device architectures. The performance of logic and
memory can be enhanced significantly by introducing a memristor, a two terminal
device with internal resistance that depends on the history of the external
bias voltage. State of the art memristors, based on metal insulator metal (MIM)
structures with insulating oxides, such as TiO2, are limited by a lack of
control over the filament formation and external control of the switching
voltage. Here, we report a class of memristors based on grain boundaries (GBs)
in single-layer MoS2 devices. Specifically, the resistance of GBs emerging from
contacts can be easily and repeatedly modulated, with switching ratios up to
1000 and a dynamic negative differential resistance (NDR). Furthermore, the
atomically thin nature of MoS2 enables tuning of the set voltage by a third
gate terminal in a field-effect geometry, which provides new functionality that
is not observed in other known memristive devices.
