Daily Overview: Today’s highlights focus on an in-depth understanding of the electronic structure of triple-layer Ruddlesden-Popper nickelates. Two independent studies, employing polarization-resolved Raman scattering and micro-focused angle-resolved photoemission spectroscopy, respectively, systematically revealed the momentum selectivity and orbital dependence of the density-wave gap in Pr₄Ni₃O₁₀ and La₄Ni₃O₁₀. One work discovered that the spin density wave gap appears only on a subset of Fermi pockets, in stark contrast to the feature in the bilayer nickelate La₃Ni₂O₇, where only the β pocket exhibits an anisotropic gap, establishing distinct gap topologies across systems with different numbers of layers. The other study, by circumventing multidomain effects, for the first time clearly distinguished intrinsic and folded bands, confirming that the density wave is driven by inter-orbital Fermi surface nesting between the α and β bands, and observed extremely strong mass renormalization of the d_z² orbital (enhancement factor up to 16.7), successfully resolving the long-controversial splitting of the triple-layer β band. These results provide key microscopic constraints for understanding the relationship between density wave instabilities and superconductivity in nickelate superconductors. arXiv submission processing window: 2026-02-02 14:13 to 2026-02-02 14:46 UTC.

1. Contrasting Momentum-Selective Spin-Density-Wave Gaps in Bilayer and Trilayer Nickelates

Summary: Using polarization-resolved electronic Raman scattering, this study systematically maps the momentum-selective spin-density-wave (SDW) gap in the trilayer nickelate La4Ni3O10. The experiments reveal that SDW-induced spectral weight redistribution occurs simultaneously on the α pocket at the Brillouin zone center and on part of the β pocket near the zone boundary, with a corresponding gap energy of approximately 55 meV, whereas no comparable spectral weight suppression is observed in the diagonal region of the β pocket, indicating that this region remains nearly gapless. This momentum-space gap topology contrasts sharply with that of the bilayer nickelate La3Ni2O7, where only the β pocket exhibits an anisotropic SDW gap. These results establish distinct momentum-space gap topologies between bilayer and trilayer nickelates, providing new constraints on the ordering wave vector of the density-wave instability and the mechanism related to superconductivity.

2. Direct Observation of Unidirectional Density Wave and Band splitting in a Single-Domain Trilayer Nickelate Pr$_4$Ni$_3$O$_{10}$

  • Relevance Score: 5.1341
  • Authors: Zhicheng Jiang, Enkang Zhang, Yuxin Wang, Zhengtai Liu, Jishan Liu, Runfeng Zhang, Xinnuo Zhang, Wenchuan Jing, Yu Huang, Qi Jiang, Mao Ye, Kun Jiang, Jun Zhao, Dawei Shen, Donglai Feng
  • Link: http://arxiv.org/abs/2602.02127v1

Summary: This study utilizes micro-focused angle-resolved photoelectron spectroscopy (μ-ARPES) on high-quality single-domain trilayer nickelate Pr₄Ni₃O₁₀ to avoid multidomain averaging effects, enabling the first clear distinction between intrinsic and folded bands. Experimental findings reveal that low-energy electronic reconstruction is primarily driven by inter-orbital Fermi surface nesting between α and β bands, and an orbital-dependent energy gap of approximately 44 meV is observed on the α pocket, resolving previous controversies regarding the magnitude and location of the density wave gap. Furthermore, the study uncovers extremely strong orbital-selective mass renormalization (mass enhancement factor up to 16.7) for the d_{z²} orbital state, far exceeding other orbitals, and successfully resolves the long-unresolved trilayer β band splitting, thereby determining the critical lower bound for outer-layer transitions. These results provide a coherent microscopic fingerprint of the density wave phase transition and electronic correlation effects in trilayer nickelates, identifying the specific nesting channels and correlation effects that govern the phase diagram.