Local peculiarities of the inhomogeneous magnetic state in LaMnO3 with deviations from stoichiometry as determined from 139La and 55Mn NMR data

The static magnetic susceptibility, the Mn-55 NMR spectra in an ordered state in a local field, and the La-139 NMR spectra in an external field were recorded for polycrystalline (LaMn)(1-2x)O-3 (x = 0, 0.03) samples with different concentrations of vacancies in the cation sublattice. It is shown that macroscopic regions with a different magnetic structure and manganese valence state (4+) are formed near vacancies in the antiferromagnetic matrix corresponding to the stoichiometric LaMnO3. An increase in the concentration of such regions results in a substantial growth of magnetic susceptibility, especially in an ordered state. The relative volume of these regions, their average size (similar to40 Angstrom), the hyperfine fields for different valence states of manganese atoms in the magnetically ordered state, and the hyperfine fields at the lanthanum atoms in the paramagnetic state were estimated from an analysis of the Mn-55 and La-139 NMR spectra.