Fig. 1: Magnetic Resonant Scattering and X-Ray Absorption of La₃Ni₂O₇.

a The crystal structure of La₃Ni₂O_7, with the pseudo tetragonal axes a_T and b_T denoting the in-plane NiO bond directions. b The intensity (scattering + background) for cuts along the (H, H, 1.86) direction through the SDW peak at various temperatures, measured at the Ni L₃ absorption edge with π incident polarization for sample A. Inset: The SDW peak amplitude, \({I}_{s}(T)=I\left(T\right)-I\left(220{K}\right)\) (red), and correlation length along the [1 1 0] direction (blue) as a function of temperature. c The energy dependence of the SDW peak amplitude, \({I}_{s}\left(\hslash \omega,100{K}\right)=I\left(\hslash \omega,100{K}\right)-I\left(\hslash \omega,220{K}\right),\) measured with π incident light at L = 1.86 through the Ni L and La M edges (blue), along with the x-ray absorption (XAS) measured via partial fluorescence yield (orange). The scattering is peaked at the Ni L resonances but is absent off resonance or at the La M₄ resonance. d The energy dependence of the SDW peak amplitude at 100 K and L = 1.86 at the Ni L₃ edge with σ and π incident light. e The Ni L₃ x-ray absorption measured using partial fluorescence yield (PFY) at base temperature (20 K) and above the SDW phase transition (200 K). f The L dependence of the SDW structure factor, I_L, at 20 K of the SDW peak at the Ni L₂ edge (870 eV) for sample B.