Strong Superexchange in a d9−δ Nickelate Revealed by Resonant Inelastic X-Ray Scattering

J. Q. Lin, 2, 3, 4 P. Villar Arribi, G. Fabbris, 6 A. S. Botana, D. Meyers, 8 H. Miao, 9 Y. Shen, D. G. Mazzone, 10 J. Feng, ∗ S. G. Chiuzbăian, 12 A. Nag, A. C. Walters, M. Garćıa-Fernández, Ke-Jin Zhou, J. Pelliciari, I. Jarrige, J. W. Freeland, Junjie Zhang, 15 J. F. Mitchell, V. Bisogni, X. Liu, † M. R. Norman, ‡ and M. P. M. Dean § Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China University of Chinese Academy of Sciences, Beijing 100049, China Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, USA Advanced Photon Source, Argonne National Laboratory, Lemont, Illinois 60439, USA Department of Physics, Arizona State University, Tempe, Arizona 85287, USA Department of Physics, Oklahoma State University, Stillwater, Oklahoma 74078, USA Material Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland Sorbonne Université, CNRS, Laboratoire de Chimie Physique-Matière et Rayonnement, UMR 7614, 4 place Jussieu, 75252 Paris Cedex 05, France Synchrotron SOLEIL, L’Orme des Merisiers, Saint-Aubin, BP 48, 91192 Gif-sur-Yvette, France Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, United Kingdom National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY 11973, USA Institute of Crystal Materials, Shandong University, Jinan, Shandong 250100, China (Dated: January 19, 2021)