Anisotropic Spin Stripe Domains in Bilayer La${}_3$Ni${}_2$O${}_7$

Abstract

The discovery of superconductivity in La${}_3$Ni${}_2$O${}_7$ under pressure has motivated the investigation of a parent spin density wave (SDW) state, which could provide the underlying pairing interaction. Here, we employ resonant soft x-ray scattering and polarimetry on thin films of bilayer La${}_3$Ni${}_2$O${}_7$ to determine that the magnetic structure of the SDW forms unidirectional diagonal spin stripes with moments lying within the NiO${}_2$ plane and perpendicular to ${\mathbf{Q}}_{SDW}$, but without evidence of the strong charge disproportionation typically associated with other nickelates. These stripes form anisotropic domains with shorter correlation lengths perpendicular versus parallel to ${\mathbf{Q}}_{SDW}$, revealing nanoscale rotational and translational symmetry breaking analogous to the cuprate and Fe-based superconductors, with possible Bloch-like antiferromagnetic domain walls separating orthogonal domains.

18 pages, 5 figures; replaced with published version. Supplementary information available at https://doi.org/10.1038/s41467-025-61653-w