"Doping evolution of the Mott–Hubbard landscape in infinite-layer nickelates"

Berit H. Goodge: Danfeng Li, Kyuho Lee, Motoki Osada, Bai Yang Wang, George A. Sawatzky,Harold Y. Hwang, and Lena F. Kourkoutis; Proceedings of the National Academy of Sciences, 01/12/21.

Additional Authors: Danfeng Li, Kyuho Lee, Motoki Osada, Bai Yang Wang, George A. Sawatzky,Harold Y. Hwang, and Lena F. Kourkoutis

Abstract:

The recent observation of superconductivity in Nd0.8Sr0.2NiO2 has raised fundamental questions about the hierarchy of the underlying electronic structure. Calculations suggest that this system falls in the Mott–Hubbard regime, rather than the charge-transfer configuration of other nickel oxides and the superconducting cuprates. Here, we use state-of-the-art, locally resolved electron energy-loss spectroscopy to directly probe the Mott–Hubbard character of Nd1xSrxNiO2. Upon doping, we observe emergent hybridization reminiscent of the Zhang–Rice singlet via the oxygen-projected states, modification of the Nd 5d states, and the systematic evolution of Ni 3d hybridization and filling. These experimental data provide direct evidence for the multiband electronic structure of the superconducting infinite-layer nickelates, particularly via the effects of hole doping on not only the oxygen but also nickel and rare-earth bands.