Local metallic and structural properties of the strongly correlated metal LaNiO 3 using 8Li β -NMR

We report β -detected NMR of ion-implanted ⁸Li in a single crystal and thin film of the strongly correlated metal LaNiO₃. Spin-lattice relaxation measurements reveal two distinct local environments, both metallic as evident from T -linear Korringa 1 /T₁ below 200 K with slopes comparable to other metals. A small approximately temperature-independent Knight shift of ∼74 ppm is observed, yielding a normalized Korringa product characteristic of substantial antiferromagnetic correlations. We find no evidence for a magnetic transition from 4 to 310 K . The similarity of these features in the two very different samples indicates that they are intrinsic and unrelated to dilute oxygen vacancies. We attribute the two environments to two distinct but similar crystallographic ⁸Li sites and not to any form of phase inhomogeneity, but this is inconsistent with the conventional rhombohedral structure of LaNiO₃, and also cannot be simply explained by the common alternative orthorhombic or monoclinic distortions.