Multiple Electronic Phase Transitions of NiO via Manipulating the NiO₆ Octahedron and Valence Control

Abstract

While the multiple Mottronic and electronic phase transitions as recently discovered in nickelates (e.g., ReNiO3) open up a new paradigm in correlated electronic applications, these applications are largely impeded by the intrinsic material metastability of the perovskite nickelates. Herein, the study demonstrates the analogous multiple electronic phase transition properties in the thermodynamically stable NiO, compared to ReNiO3, from both perspectives of band gap regulation and orbital filling regulation. The adjustment in band gap of NiO with t2g6eg2 orbital configuration is achieved via establishing biaxial tensile or compressive interfacial strains that increase or reduce the material resistivity, respectively. The relaxor ferroelectricity of 0.7Pb(Mg2/3Nb1/3)O3‐0.3PbTiO3 (PMNPT) further enables an electric field adjustable resistance switch (ΔR/R) within NiO/PMNPT heterostructure with higher performances (e.g., ΔR/R of 82% upon a bias voltage of 20 V) than the reported oxides/PMNPT heterostructure. Furthermore, the magnitude in resistance switch of the tensile strained NiO via hydrogenation associated Mottronic process reaches ≈1011 that exceeds the previously reported ones. This study highlights the higher material stability and easier growth of NiO, compared to ReNiO3, with analogous multiple Mottronic and electronic phase transition properties that pave the way to its practical applications in correlated electronics.