Resolving the electronic ground state of La₃Ni₂O₇-δ films

摘要

The recent discovery of a superconductivity signature in La₃Ni₂O₇-δ under a pressure of 14 GPa, with a superconducting transition temperature of around 80 K, has attracted considerable attention. An important aspect of investigating electronic structures is discerning the extent to which the electronic ground state of La₃Ni₂O₇-δ resembles the parent state of the cuprate superconductor, a charge transfer insulator with long-range antiferromagnetism. Through X-ray absorption spectroscopy, we reveal the influence of oxygen ligands on the electronic ground states of the Ni ions, displaying a charge transfer nature akin to cuprate but with distinct orbital configurations. Additionally, in La₃Ni₂O₇-δ films, we detect a superlattice reflection (1/4, 1/4, L) at the Ni L absorption edge using resonant X-ray scattering measurements. Further examination of the resonance profile indicates that the reflection originates from the Ni d orbitals. B_y evaluating the reflection’s azimuthal angle dependence, we confirm the presence of collinear antiferromagnetic spin ordering and charge-like anisotropy ordered with the same periodicity. Our findings reveal a microscopic relationship between these two components in the temperature dependence of the scattering intensity of the reflection. This investigation enriches our understanding of high-temperature superconductivity in La₃Ni₂O₇-δ under high pressure.

材料

• La₃Ni₂O₇-δ

方法

• X-ray absorption spectroscopy (XAS)
• resonant X-ray scattering (RXS)

关键词

• charge transfer insulator
• antiferromagnetism
• collinear antiferromagnetic spin ordering
• charge like anisotropy

亮点

• Resolving the electronic ground state of La₃Ni₂O₇-δ films reveals a charge transfer nature and collinear antiferromagnetic spin ordering.
• This investigation enriches the understanding of high-temperature superconductivity in La₃Ni₂O₇-δ under high pressure.

结论

• Through X-ray absorption spectroscopy, the influence of oxygen ligands on the electronic ground states of the Ni ions is revealed, displaying a charge transfer nature akin to cuprate but with distinct orbital configurations.
• In La₃Ni₂O₇-δ films, a superlattice reflection (1/4, 1/4, L) at the Ni L absorption edge is detected using resonant X-ray scattering measurements.
• B_y evaluating the reflection’s azimuthal angle dependence, the presence of collinear antiferromagnetic spin ordering and charge-like anisotropy ordered with the same periodicity is confirmed.
• A microscopic relationship between these two components in the temperature dependence of the scattering intensity is found.

主要论断

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研究流程

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