Abstract The synthesis of large bulk nickelate single crystals remains challenging. We demonstrated room-temperature biaxial magnetic alignment of polycrystalline La3Ni2O7+δ (δ = 0) using a modulated rotating field (MRF). Phase-pure powders (~5 μm) were aligned under 7 T-MRF during epoxy curing, exploiting triaxial susceptibility (χa > χb > χc). XRD and pole-figures confirm: Δϕ =4° in-plane orientation degrees and orthorhombic twin domains via (h00)/(0k0) peaks and fourfold symmetry. These twins, analogous to cuprates but distinct in NiO6 origin, provide the first crystallographic evidence of domain microstructure in nickelates, enabling direction-resolved studies of anisotropy of density-order phase and superconductivity obscured by heterogeneity.
Ali et al. (Thu,) studied this question.