Magnetic properties of nanoparticle La0.7Ca0.3MnO3 under applied hydrostatic pressure
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Pressure effects on magnetic properties of two La0.7Ca0.3MnO3 nanoparticle samples with different mean particle sizes were investigated. Both the samples were prepared by the glycine-nitrate method: sample S-as-prepared (10 nm), and sample S-900-subsequently annealed at 900 A degrees C for 2 h (50 nm). Magnetization measurements revealed remarkable differences in magnetic properties with the applied pressure up to 0.75 GPa: (i) for S sample, both transition temperatures, para-to-ferromagnetic T (C) = 120 K and spin-glass-like transition T (f) = 102 K, decrease with the pressure with the respective pressure coefficients dT (C)/dP = -2.9 K/GPa and dT (f)/dP = -4.4 K/GPa; (ii) for S-900 sample, para-to-ferromagnetic transition temperature T (C) = 261 K increases with pressure with the pressure coefficient dT (C)/dP = 14.8 K/GPa. At the same time, saturation magnetization M (S) recorded at 10 K decreases/increases with pressure for S/S-900 sample, respectively. Explanation of these unusual... pressure effects on the magnetism of sample S is proposed within the scenario of the combined contributions of two types of disorders present in the system: surface disorder introduced by the particle shell, and structural disorder of the particle core caused by the prominent Jahn-Teller distortion. Both disorders tend to vanish with the annealing of the system (i.e., with the nanoparticle growth), and so the behavior of the sample S-900 is similar to that previously observed for the bulk counterpart.
Кључне речи:Manganites / Nanoparticles / Disorder / Pressure effect / Magnetic properties
Извор:Journal of Nanoparticle Research, 2010, 12, 4, 1299-1306
- Serbian-Slovak bilateral project [SK-SRB-00207], Serbian-Slovak national projects [P-141027, VEGA 2/0057/10]
ISSN: 1388-0764 (print)