Role of surface on magnetic properties of La.sub.1-x./sub.Sr.sub.x./sub.MnO.sub.3+δ./sub. nanocrystallites

0450598 - FZÚ 2016 RIV US eng J - Journal Article
Jirák, Zdeněk - Kačenka, Michal - Kaman, Ondřej - Maryško, Miroslav - Belozerova, N.M. - Kichanov, S.E. - Kozlenko, D. P.
Role of surface on magnetic properties of La_1-xSr_xMnO_3+δ nanocrystallites.
IEEE Transactions on Magnetics. Roč. 51, č. 11 (2015), s. 1000204. ISSN 0018-9464. E-ISSN 1941-0069
R&D Projects: GA ČR GA15-10088S
Institutional support: RVO:68378271
Keywords : magnetic nanoparticles * neutron diffraction * perovskite manganite * phase separation
Subject RIV: BM - Solid Matter Physics ; Magnetism
Impact factor: 1.277, year: 2015

The magnetic La1–xSrxMnO3 particles of ≈50 nm size have been prepared in the flux of sodium nitrite. A detailed magnetic study, including the neutron diffraction at zero and high pressures, has been performed for x = 0.28 and 0.37, as well as on comparative samples prepared via sol-gel route. Based on these experiments we conclude that the molten salt prepared particles show significant oxygen excess δ > 0 that can be ascribed mainly to the surface oxygen chemisorption. As a consequence, the valence of Mn ions is shifted towards a higher oxidation state and this shift probably exhibits a pronounced radial distribution in the particles. We suggest that such overdoping is an additional reason for “magnetically dead” shell in manganite nanoparticles and is also the source of surface stress that compresses the particle core. Such compressive stress drives the magnetic ground state of the composition x = 0.37 towards a mixture of FM and A-type AFM ordering.
Permanent Link: http://hdl.handle.net/11104/0251871