Daily Overview: Today’s highlighted work focuses on gaining a deeper understanding of the electronic structure of infinite-layer nickelates, particularly the orbital origin of the A-pocket and the controversy surrounding its identification in photoemission spectra. [1] By combining DFT+DMFT to study bulk NdNiO2 and employing a plane-wave final-state approximation to simulate polarization-dependent ARPES, the study shows that the A-pocket is not of single-orbital character but is formed through strong hybridization among interstitial s, Nd-dxy, and Ni-dxz/yz orbitals, with all three contributing significantly near the DMFT Fermi level. The simulations reproduce the main polarization-dependent Fermi surface features observed experimentally and reveal that removing the interstitial s matrix element leads to pronounced disagreement with experiment, whereas suppressing the Nd-dxy or Ni-dxz/yz matrix elements has only a minor effect. This work emphasizes that, when assigning the microscopic orbital origins of low-energy spectral features in such nickelates, both orbital hybridization and photoemission matrix elements must be treated simultaneously, providing important constraints for understanding the electronic structure relevant to infinite-layer nickel-based superconductivity. arXiv submission processing window: 2026-09-21 00:00 to 2026-09-21 00:00 UTC.

1. Orbital character and photoemission signatures of the A-pocket in infinite-layer nickelates

Summary: To address the controversy over the orbital origin of the A-pocket in infinite-layer nickelates, the authors combined density functional theory (DFT) with dynamical mean-field theory (DMFT) to study bulk NdNiO2 and employed a plane-wave final-state approximation to simulate polarization-dependent angle-resolved photoemission spectroscopy (ARPES). The results show that the A-pocket is not a single orbital but is formed by strong hybridization among interstitial s, Nd-dxy, and Ni-dxz/yz orbitals; near the Fermi level in the DMFT calculations, all three contribute significantly. The simulations reproduce the main polarization-dependent Fermi surface features observed experimentally; removing the interstitial s matrix element, even though its spectral weight is not dominant, leads to clear disagreement with experiment, whereas suppressing the Nd-dxy or Ni-dxz/yz matrix elements has only a minor effect because these matrix elements are small at the Brillouin zone corners. Therefore, when identifying the microscopic orbital origin of the low-energy spectral features in such materials, one must simultaneously account for orbital hybridization and photoemission matrix elements.