Magnetic resonance properties of La0.8Sr0.2MnO3 small particles

Single-phase nanoparticles of La0.8Sr0.2MnO3 have been synthesized via the freeze-drying synthesis technique and subsequent high-energy ball-milling. Transmission electron microscopy images showed aggregates of 300-500 nm in size which consisted of spherical particles characterized by average diameter 30-50 nm. Magnetic and magnetic resonance experiments on the nanoparticles allow us to determine their Curie temperature TC = 323 ± 3 K, which was markedly higher than value 302 ± 2 K of corresponding bulk single-crystalline sample. Short-range ferromagnetic correlations can be responsible for increasing of TC in the manganite nanoparticles. We also found a significant enhancement of magnetic spin relaxation in the nanoparticles in comparison with the bulk samples. The observed effect can be explained by a strengthening of the spin-lattice relaxation for Mn3+ ions in the La0.8Sr0.2MnO3 nanoparticles due to the increase of non-cubic components of the crystal field.