Colossal resistance switching and band gap modulation in a perovskite nickelate by electron doping

The electronic properties of correlated oxides are exceptionally sensitive to the orbital occupancy of electrons. Here we report an electron doping strategy via a chemical route, where interstitial dopants (for example, hydrogen) can be reversibly intercalated, realizing a sharp phase transition in a model correlated perovskite nickelate SmNiO₃. The electron configuration of e_g orbital of in Ni³⁺ t_2g ⁶e_g¹ in SmNiO₃ is modified by injecting and anchoring an extra electron, forming a strongly correlated Ni ²⁺ t_2g⁶e_g² structure leading to the emergence of a new insulating phase. A reversible resistivity modulation greater than eight orders of magnitude is demonstrated at room temperature. A solid-state room temperature non-volatile proton-gated phase-change transistor is demonstrated based on this principle, which may inform new materials design for correlated oxide devices. Electron doping-driven phase transition accompanied by large conductance changes and band gap modulation opens up new directions to explore emerging electronic and photonic devices with correlated oxide systems.