Strong Superexchange in a d^{9-δ} Nickelate Revealed by Resonant Inelastic X-Ray Scattering.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Materials

Background:

• Superconductivity in d-electron systems, particularly nickelates, is a significant area of research.
• Understanding the underlying physics, especially magnetic superexchange, is crucial for realizing high-temperature superconductivity.
• The d^{9-δ} electronic configuration in nickelates presents unique properties compared to cuprates.

Purpose of the Study:

• To investigate the magnitude of magnetic superexchange in trilayer nickelates (R₄Ni₃O₈).
• To determine if d^{9-δ} nickelates can support cuprate-like superconductivity.
• To establish the relationship between superexchange, Ni-O hybridization, and superconductivity in layered nickelates.

Main Methods:

• Utilized Ni L-edge and O K-edge spectroscopy on R₄Ni₃O₈ (R=La, Pr) samples.
• Performed theoretical modeling to analyze spectroscopic data.
• Quantified magnon energy scale and magnetic exchange interactions.

Main Results:

• Observed a magnon energy scale of approximately 80 meV.
• Determined a nearest-neighbor magnetic exchange (J) of 69(4) meV, indicating large superexchange.
• Estimated Ni-O hybridization from O K-edge spectroscopy.

Conclusions:

• d^{9-δ} nickelates can host a substantial magnetic superexchange.
• Trilayer nickelates represent an intermediate material class between infinite-layer nickelates and cuprates.
• Layered nickelates offer a platform for studying the role of superexchange in superconductivity.