- Open Access
Lattice-Charge Coupling in a Trilayer Nickelate with Intertwined Density Wave Order
Phys. Rev. X 16, 011013 – Published 23 January, 2026
DOI: https://doi.org/10.1103/s5j9-cbg7
Abstract
Intertwined charge and spin correlations are ubiquitous in a wide range of transition metal oxides and are often perceived as intimately related to unconventional superconductivity. Theoretically envisioned as driven by strong electronic correlations, the intertwined order is usually found to be strongly coupled to the lattice as signaled by pronounced phonon softening. Recently, both charge and spin density waves (CDW and SDW) and superconductivity have been discovered in several Ruddlesden-Popper (RP) nickelates, in particular trilayer nickelates (, La). The nature of the intertwined order and the role of lattice-charge coupling are at the heart of the debate about these materials. Using inelastic x-ray scattering, we mapped the low-energy phonon dispersions in and found no evidence of softening near the CDW wave vector over a wide temperature range, which contrasts with the pronounced anomalies frequently observed in cuprate superconductors. Calculations of the electronic susceptibility revealed a peak at the observed SDW ordering vector but not at the CDW wave vector. Our experimental and theoretical findings highlight the crucial role of the spin degree of freedom and establish a foundation for understanding the interplay between superconductivity and density-wave transitions in RP nickelate superconductors and beyond.
Physics Subject Headings (PhySH)
Popular Summary
Understanding the relationship between intertwined charge and spin density wave (CDW and SDW) order and superconductivity remains a central, unresolved question in condensed matter physics. This is made more challenging by the involvement of the lattice, as revealed by the phonon softening observed in many materials like cuprates. Using high-resolution inelastic x-ray scattering, we reveal the surprising absence of low-energy phonon anomalies at the CDW wave vector in the intertwined CDW and SDW nickelate superconductors (, La). Density-functional theory and electron susceptibility calculations further revealed that the intertwined order is magnetically driven. Our results contrast with past observations in cuprates and highlight the crucial role of the spin degree of freedom in nickelate superconductors.
Article Text
Supplemental Material
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