Structural, magnetic, and physical properties of La_(1–x)MnO_3±δnano-manganite

A detailed structural, magnetic and physics properties of La1−xMnO3±δ (LMO) nanomanganites were investigated to find out the role of cationic vacancies (La vacancy with Mn3+/Mn4+) in grain size modulation. Crystal structure and phase analysis of all samples were carried out by Rietveld refinement of high-resolution XRD and neutron diffraction data. We report here, the oxygen content in studied LMO compound decreases with increase in La vacancies in parent site and a parasitic Mn3O4 phase has been evolved in the range of 0.9 ≥ La/Mn ≥ 0.7. Para to ferro magnetic transition temperature (TC) of all nanometric samples (La/Mn < 0.9) was found at high temperature side (≥260 K) whereas, the same for bulk one (La/Mn ≥ 0.9) was around 160 K. The enhancement of TC (~70 K) with size reduction is attributed to broadening of bandwidth due to compaction of MnO6 octahedra in system unit cell. In bulk sample, a secondary cluster/spin glassy phase is found below 50 K, whereas the glassy phase has been suppressed in nanoscale. Field-dependent magneto-resistance measurements are also carried out for all samples at different temperatures to get a profound insight of magneto-transport dynamics of the present system.