Formation of an Antiferromagnetic Metal Phase in the Electron-Doped Sr0.98La0.02MnO3 Oxide According to 17O NMR Data

Abstract

The spin density distribution of itinerant electrons, neg, and their effect on pairwise correlations of localized spins S(t2g) of Mn4+ ions in cubic Sr1 − xLaxMnO3 antiferromagnet (x = 0.02, TN = 230 K, G type magnetic structure) is studied experimentally by nuclear magnetic resonance on 17O nuclei. The regions with neg > x, in which the local spin susceptibility of pairs of Mn atoms follows the dependence χ ∼ (T − Θ)−1 with Θ = 20(5) K, indicating the growth of ferromagnetic spin correlations of neighboring magnetic ions in these domains, are found in the paramagnetic phase. The fraction of Mn-O-Mn bonds (neg > x) increases with the decrease in the temperature. The interpenetrating meshes of Mn-O-Mn bonds with different densities of itinerant eg electrons form an antiferromagnetic metal phase below TN. The role of weak localization effects is discussed as the main origin of the magnetic inhomogeneity of the antiferromagnetic metal phase in Sr0.98La0.02MnO3.