The investigation is urgent due to the urgency of preparation and study of nanostructured metal oxides where unique magnetic and transport properties are combined. Manganite-lanthanum perovskites possessing colossal magnetoresistance are among them [1, 2].

Different nanotechnologies have been used: 1- mechanical mixing and grinding of powder oxides and salt of respective metals; 2 – combined precipitation of their nitrate salts; 3 – hydrolytic sputtering.

Methods of X-ray diffraction, low-temperature adsorption of argon, resistive, magnetic (including the ⁵⁵Mn NMR) ones [3] have been applied to investigate phase composition of powder, their dispersity and presence of defects in the structure, as well as density (γ), resistivity (ρ), coercive force (Hc), magnetic susceptibility (χ) and magnetoresistance (MR = Δρ/ρ₀) of nanopowder pressings, sintered ceramics and thin film prepared from nonstoichiometric La_0.6Sr_0.3Mn_1.1O₃ [4].

Differences in physical and chemical properties of nanopowder produced by different technologies have been investigated. It is shown that with the increase of high hydrostatic pressure (HHP) to P=1.6 GPa γ, Hc, MR are increasing and ρ is decreasing.

Regularities have been determined for temperature and pressure dependences of χ and ρ; the tunnel character of conductivity and magnetoresistance at interparticle contacts, and for the relationship between MR, particle size and pressure. A comparative analysis of magnetoresistance mechanism and differences for nanopowder pressings, sintered ceramics and thin film has been performed.

1. Nagaev E.L. Phys. Rep. 346, 387 (2001).

2. Mandal P., Ghosh B. Phys. Rev. B 69, 014422 (2003).

3. Pashchenko V.P. et al. Low Temp. Phys. 29, 910 (2003).

4. Pashchenko V.P. et al. Technical Physics 50, 1497 (2005).

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