Electronic Structure, Magnetic Interactions and Charge Order in Low Valence Nickelates Probed by Resonant Inelastic X-Ray Scattering

After a 30-year quest, researchers recently succeeded in realizing superconductivity in low-valence nickelates [1]. This ignited a vigorous debate regarding the essential electronic properties of these materials and their similarity to cuprates. Some important questions include: Do these materials have appreciable oxygen charge-transfer character and superexchange akin to the cuprates or are they in a distinct Mott-Hubbard regime where oxygen plays a minimal role and superexchange is negligible? Given that cuprates have a propensity to host proximate competing phases such as charge and spin order, one might ask whether the nickelate’s phase diagrams also host competing orders and to what extent they are similar to those in cuprates? In this talk, I will describe our use of resonant inelastic x-ray scattering to solve these questions [2-4].<br/><br/><b>References</b><br/>1. Danfeng Li, Kyuho Lee, Bai Yang Wang, Motoki Osada, Samuel Crossley, Hye Ryoung Lee, Yi Cui, Yasuyuki Hikita & Harold Y. Hwang, Nature 572, 624–627 (2019)<br/>2. Strong Superexchange in a d^9-δ Nickelate Revealed by Resonant Inelastic X-Ray Scattering, J. Q. Lin, P. Villar Arribi, G. Fabbris, A. S. Botana, D. Meyers, H. Miao, Y. Shen, D. G. Mazzone, J. Feng, S. G. Chiuzbaian, A. Nag, A. C. Walters, M. Garcia-Fernandez, Ke-Jin Zhou, J. Pelliciari, I. Jarrige, J. W. Freeland, Junjie Zhang, J. F. Mitchell, V. Bisogni, X. Liu, M. R. Norman, and M. P. M. Dean, Phys. Rev. Lett. 126, 087001 (2021)<br/>3. Role of Oxygen States in the Low Valence Nickelate La₄Ni₃O₈, Y. Shen, J. Sears, G. Fabbris, J. Li, J. Pelliciari, I. Jarrige, Xi He, I. Bozovic, M. Mitrano, Junjie Zhang, J. F. Mitchell, A. S. Botana, V. Bisogni, M. R. Norman, S. Johnston, and M. P. M. Dean, Phys. Rev. X 12, 011055 (2022)<br/>4. Electronic character of charge order in square planar low valence nickelates, Y. Shen, J. Sears, G. Fabbris, J. Li, J. Pelliciari, M. Mitrano, W. He, Junjie Zhang, J. F. Mitchell, V. Bisogni, M. R. Norman, S. Johnston, and M. P. M. Dean, Phys. Rev. X 13, 011021 (2023)