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 eg orbital of Ni(3+) t2g(6)eg(1) in SmNiO3 is modified by injecting and anchoring an extra electron, forming a strongly correlated Ni(2+) t2g(6)eg(2) 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.