Electronic and magnetic excitations in La3Ni2O7

Xiaoyang Chen; Jaewon Choi; Zhicheng Jiang; Jiong Mei; Kun Jiang; Jie Li; Stefano Agrestini; Mirian Garcia-Fernandez; Hualei Sun; Xing Huang; Dawei Shen; Meng Wang; Jiangping Hu; Yi Lu; Ke-Jin Zhou; Donglai Feng

doi:10.1038/s41467-024-53863-5

Electronic and magnetic excitations in La₃Ni₂O₇

Nat Commun. 2024 Nov 6;15(1):9597. doi: 10.1038/s41467-024-53863-5.

Authors

Xiaoyang Chen^#¹, Jaewon Choi^#², Zhicheng Jiang³, Jiong Mei^{4

5}, Kun Jiang^{4

5}, Jie Li⁶, Stefano Agrestini², Mirian Garcia-Fernandez², Hualei Sun⁷, Xing Huang⁸, Dawei Shen³, Meng Wang⁸, Jiangping Hu^{4

9}, Yi Lu^{10

11}, Ke-Jin Zhou¹², Donglai Feng^{13

14

15}

Affiliations

¹ State Key Laboratory of Surface Physics, Department of Physics, and Advanced Materials Laboratory, Fudan University, Shanghai, China.
² Diamond Light Source, Didcot, UK.
³ National Synchrotron Radiation Laboratory and School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, China.
⁴ Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, China.
⁵ School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, China.
⁶ National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing, China.
⁷ School of Science, Sun Yat-Sen University, Shenzhen, Guangdong, China.
⁸ Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices, School of Physics, Sun Yat-Sen University, Guangzhou, Guangdong, China.
⁹ New Cornerstone Science Laboratory, Beijing, China.
¹⁰ National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing, China. [email protected].
¹¹ Collaborative Innovation Center of Advanced Microstructures, Nanjing, China. [email protected].
¹² Diamond Light Source, Didcot, UK. [email protected].
¹³ National Synchrotron Radiation Laboratory and School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, China. [email protected].
¹⁴ Collaborative Innovation Center of Advanced Microstructures, Nanjing, China. [email protected].
¹⁵ New Cornerstone Science Laboratory, University of Science and Technology of China, Hefei, China. [email protected].

^# Contributed equally.

Abstract

High-temperature superconductivity was discovered in the pressurized nickelate La₃Ni₂O₇ which has a unique bilayer structure and mixed valence state of nickel. The properties at ambient pressure contain crucial information of the fundamental interactions and bosons mediating superconducting pairing. Here, using X-ray absorption spectroscopy and resonant inelastic X-ray scattering, we identified that Ni 3 $d_{x^{2} - y^{2}}$ , Ni 3 $d_{z^{2}}$ , and ligand oxygen 2p orbitals dominate the low-energy physics with a small charge-transfer energy. Well-defined optical-like magnetic excitations soften into quasi-static spin-density-wave ordering, evidencing the strong electronic correlation and rich magnetic properties. Based on an effective Heisenberg spin model, we extract a much stronger inter-layer effective magnetic superexchange than the intra-layer ones and propose two viable magnetic structures. Our findings emphasize that the Ni 3 $d_{z^{2}}$ orbital bonding within the bilayer induces novel electronic and magnetic excitations, setting the stage for further exploration of La₃Ni₂O₇ superconductor.