Dimensionality-enhanced resistivity switching in NdNiO3 films via ionic liquid gating

Achieving flexible and robust resistive switching in functional oxide heterostructures is critical to solid-state neuromorphic computing. Existing efforts for realizing high switching ratios and consistent device performance across repeated electric-field cycles are often empirical and involve trying different film materials and substrates. In this work, we directly compare the performance of ionic-liquid-gated (ILG) NdNiO3 (NNO) on NdGaO3 (NGO) (001) and (110) substrates. We demonstrate an 1000-fold resistivity switching enhancement in NNO on the NGO (001) substrates, and ascribe the enhancement to anisotropic, unidirectional lattice expansion during the oxygen reduction using operando X-ray diffraction. We further examine the cycle-over-cycle performance of these films and show the persistent switching ratio enhancement in the NNO/NGO (001) device is correlated with the formation of quasi-1D stripe-like domains in the as-grown films. The mesoscale domain morphology in the two films was obtained combining dark field X-ray microscopy (DFXM) and electron beam back scattering (EBSD). Our work provides a rational pathway towards engineering non-volatile synaptic memories in a family of materials for the neuromorphic device.