Nature of the density-wave order in ambient-pressure La3Ni2O7
In plain words
At normal pressure La3Ni2O7 does not superconduct but forms a density wave, a periodic pattern of spins and possibly charges, near 150 K; its form and its link to superconductivity are uncertain.
Precise statement
Identify the spin and charge density-wave order of La3Ni2O7 at ambient pressure (onset near 150 K): wavevector, moment size and arrangement on the bilayer, and any charge component. Determine whether suppression of this order under pressure or strain is necessary for superconductivity. An answer is a refined magnetic structure from neutron or resonant x-ray scattering plus a phase diagram showing where the order vanishes relative to the superconducting onset.
What would settle it
Single-crystal neutron diffraction and resonant x-ray scattering on stoichiometric crystals, followed under pressure to the superconducting regime.