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

TL;DR

This study uses micro-focused ARPES to directly observe unidirectional density wave and band splitting in a single-domain trilayer nickelate, revealing the electronic mechanisms behind the phase transition.

Contribution

It provides the first direct spectroscopic evidence of the density wave origin, orbital-dependent gaps, and intrinsic band splitting in Pr4Ni3O10, clarifying the electronic structure of trilayer nickelates.

Findings

Identification of inter-orbital nesting between α and β bands

Observation of a ~44 meV orbital-dependent gap on the α pocket

Resolution of intrinsic trilayer β-band splitting

Abstract

Unraveling the interplay between density-wave (DW) instabilities and multi-orbital physics is critical for understanding superconductivity in Ruddlesden-Popper nickelates, yet intrinsic electronic features have been persistently obscured by material inhomogeneity and thus the multi-domain averaging effect. Here, we employ micro-focused angle-resolved photoemission spectroscopy ($\mu$-ARPES) on single-domain Pr$_4$Ni$_3$O$_{10}$ to disentangle the complex hierarchy of intrinsic and back-folded bands, explicitly identifying the electronic states driving the DW phase transition. We provide decisive spectroscopic evidence that the low-energy reconstruction is governed by inter-orbital nesting between the $\alpha$ and $\beta$ bands. Specifically, we resolve a orbital-dependent gap of $\sim44$ meV on the $\alpha$ pocket, a value quantitatively consistent with prior measurements, unifying previously conflicting experimental reports regarding the locus and magnitude of the DW gap. Furthermore, we reveal strong orbital-selective mass renormalization in the $d_{z^2}$ states and successfully resolve the long-sought intrinsic trilayer $\beta$-band splitting, establishing a critical lower bound for the outer-layer hopping. These results define a coherent microscopic fingerprint for the trilayer nickelates, identifying the specific nesting channels and correlation effects that underpin the phase diagram.