Current-controlled negative differential resistance in small-polaron hopping system

Current-controlled negative differential resistance (CC-NDR) phenomenon attracts a lot of interest for fabricating the access devices of nonvolatile memory based on crossbar array architectures. However, simple, bipolar, two-terminal commercial devices that exhibit CC-NDR are currently lacking because a number of critical characteristics needed to be met for such application. Here, we report the CC-NDR observed in Mn_1.56Co_0.96Ni_0.48O₄ (MCNO)- a small-polaron hopping material. Our experimental data and simulation reveal that the CC-NDR arises from self-heating effect due to the nature of strong electron-phonon coupling in small-polaron hopping system. The reported CC-NDR exhibits adjustable threshold voltage from 10^-3 to 10² V, on-state current from 10⁵ to 10⁸ A/cm² and off-state current is as low as ∼10 A/cm² depending on device dimensions, thermal isolation condition, environmental temperature and activation energy of material. Uniquely, unlike in NbO₂, Nb₂O₅, TiO₂, TaO_x et. al. materials, the CC-NDR in MCNO is more stable and reliable, because it does not undergo any electroforming process. These traits make MCNO a very potential candidate for CC-NDR devices.