Daily Overview: Today’s highlight work focuses on gaining an in-depth understanding of the electronic structure and magnetic tunability of the novel d⁹ double-infinite-layer nickelate La₃Ni₂O₅F. First-principles calculations reveal that this system is kinetically stable, with its electronic structure dominated by highly two-dimensional Ni‑d_{x²−y²} states, exhibiting cuprate-like Fermi surface features. Due to self-doping effects from the rare-earth layer, the effective filling is approximately d^{1·2}, and the charge-transfer energy also falls within the cuprate regime. These electronic characteristics show remarkable robustness under chemical pressure and epitaxial strain, with only moderate modulation of the Ni‑d_{x²−y²} filling. Concurrently, the system exhibits nearly degenerate magnetic configurations with various in-plane and inter-plane spin arrangements, and compressive strain can further enhance magnetic frustration without significantly altering the electronic structure. This work establishes La₃Ni₂O₅F as a promising cuprate analog and highlights the potential of lattice engineering for finely tuning its electronic and magnetic properties. arXiv submission processing window: 2026-07-27 00:00 to 2026-07-27 00:00 UTC.

1. Structural stability, electronic structure, and magnetism of the $d^9$ double infinite-layer La$_3$Ni$_2$O$_5$F under chemical pressure and epitaxial strain

Summary: Using first-principles calculations, this study investigates the structural stability, electronic structure, and magnetism of the newly synthesized double-infinite-layer oxyfluoride La₃Ni₂O₅F, along with the effects of chemical pressure and epitaxial strain. The phonon spectrum confirms the dynamical stability of the crystal structure, while the electronic structure exhibits a highly two-dimensional, cuprate-like Fermi surface dominated by Ni-d_(x²−y²) states, with an effective filling of approximately d^1.2 resulting from self-doping by rare-earth ions, and a charge-transfer energy close to the cuprate regime. These electronic features remain remarkably robust under chemical pressure and epitaxial strain, with only moderate changes in the Ni-d_(x²−y²) filling. Spin-polarized calculations reveal multiple near-degenerate magnetic configurations with various in-plane and out-of-plane spin arrangements, and compressive strain further enhances magnetic frustration without significantly altering the electronic structure. Consequently, La₃Ni₂O₅F is established as a promising cuprate analog, and lattice engineering can effectively provide fine-tuning of its electronic and magnetic properties.