Electric Pulse Induced Resistive Switching in the Narrow Gap Mott Insulator GaMo4S8

We report here on resistive switching measurements on GaMo4S8 a lacunar spinel compound with tetrahedral Mo4 clusters filled with 11 electrons. Alike other clustered lacunar spinel compounds with 7 or 8 electrons per cluster, this narrow gap Mott Insulator exhibits both a volatile and a non-volatile unipolar resistive switching. We found that the volatile resistive switching appears above a threshold electric field in the 7 kV/cm range. For electric field much larger than this threshold, the resistive switching becomes non-volatile. Successive electric pulses allow switching back and forth between high and low resistance states. All these results demonstrate that the narrow gap Mott insulator compound GaMo4S8 could be a relevant candidate for a new type of non-volatile memory based on an electric field induced breakdown of the Mott insulating state.