Valence, charge transfer, and orbital-dependent correlation in bilayer nickelates ${\mathrm{Nd}}_3{\mathrm{Ni}}_2{\mathrm{O}}_7$

Journal Article · 31 March 2025 · Physical Review. B

DOI: https://doi.org/10.1103/PhysRevB.111.165101 · OSTI ID:2545119

Takegami, Daisuke ; Okauchi, Takaki ; Morales, Edgar Abarca ; Fujinuma, Koto ; Furo, Mizuki ; Yoshimura, Masato; Tsuei, Ku-Ding; Pan, Grace A. ; Segedin, Dan Ferenc; Song, Qi; Paik, Hanjong ; Brooks, Charles M. ; Mundy, Julia A. ; Mizokawa, Takashi ; Tjeng, Liu Hao ; Goodge, Berit H. ; Hariki, Atsushi

We examine the bulk electronic structure of ${\mathrm{Nd}}_3{\mathrm{Ni}}_2{\mathrm{O}}_7$ using Ni $2p$ core-level hard x-ray photoemission spectroscopy combined with density functional theory $+$ dynamical mean-field theory. Our results reveal a large deviation of the Ni $3d$ occupation from the formal ${\mathrm{Ni}}^{2.5+}$ valency, highlighting the importance of the charge transfer from oxygen ligands. We find that the dominant $d^8$ configuration is accompanied by nearly equal contributions from $d^7$ and $d^9$ states, exhibiting an unusual valence state among Ni-based oxides. Finally, we discuss the Ni $d_{x^2-y^2}$ and $d_{z^2}$ orbital-dependent hybridization, correlation and local spin dynamics. Published by the American Physical Society 2025

• Sponsoring Organization: USDOE
• Grant/Contract Number: SC0021925
• OSTI ID: 2545119
• Journal Information: Physical Review. B, Journal Name: Physical Review. B Journal Issue: 16 Vol. 111; ISSN 2469-9950; ISSN PRBMDO
• Publisher: American Physical SocietyCopyright Statement
• Country of Publication: United States
• Language: English