Unveiling Strong Ion–Electron–Lattice Coupling and Electronic Antidoping in Hydrogenated Perovskite Nickelate

Abstract

AbstractDespite being highly promising for applications in emergent electronic devices, decoding both the ion–electron–lattice coupling in correlated materials at the atomic scale and the electronic band structure remains a big challenge due to the strong and complex correlation among these degrees of freedom. Here, taking an epitaxial thin film of perovskite nickelate NdNiO3 as a model system, hydrogen‐ion‐induced giant lattice distortion and enhanced NiO6 octahedra tilting/rotation are demonstrated, which leads to a new robust hydrogenated HNdNiO3 phase with lattice expansion larger than 10% on a series of substrates. Moreover, under the effect of ion–electron synergistic doping, it is found that the proposed electronic antidoping, i.e., the doped electrons mainly fill the ground‐state oxygen 2p holes instead of changing the Ni oxidation state from Ni3+ to Ni2+, dominates the metal–insulator transition. Meanwhile, lattice modification with enhanced Ni–O–Ni bond tilting or rotation mainly modifies the orbital density of states near the Fermi level. Last, by electric‐field‐controlled hydrogen‐ion intercalation and its strong coupling to the lattice and electron charge, selective micrometer‐scale patterns with distinct structural and electronic states are fabricated. The results provide direct evidence for a strong ion–electron–lattice coupling in correlated physics and exhibit its potential applications in designing novel materials and devices.