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Size dependence of magnetic properties of Sm0.43Ca0.57MnO3 nanoparticles with average size of 15–60 nm has been investigated. Charge ordering, characteristic for the bulk form of this material, was found to be gradually suppressed with decreasing particle size and fully disappearing in 15 nm nanoparticles. Onsets of ferromagnetic contributions to the magnetization appear below 90 K, independently on the particle size, while spontaneous magnetization at 10 K increases with decreasing particle size. Magnetic hysteresis loops exhibit size dependent exchange bias effect manifested by horizontal HEB and vertical MEB shifts, appearing after field cooling. Variation of HEB and MEB shows opposite size dependences; HEB decreases while MEB increases with decreasing particle size. For large 60 nm particles, HEB decreases monotonously with increasing temperature, while for the smallest 15 nm particles it shows surprising nonmonotonic temperature dependence. Size and temperature dependences are discussed in terms of m...

We report the structural and magnetic properties of La0.2Ca0.8MnO3 nanoparticles synthesized by a chemical route, having an average diameter of 15 nm. Synchrotron experiments performed in the temperature range 80−300 K have shown that below 200 K a structural transition from room temperature orthorhombic Pnma to monoclinic P21/m space group, associated with orbital ordering, survives in studied particles, although this transition is highly suppressed in comparison with that of the bulk. The magnetization of these particles exhibits the appearance of a ferromagnetic contribution from the shell at T > 200 K, antiferromagnetic ordering within the particle core at TN ∼ 140 K, and the emergence of another ferromagnetic contribution at T < 100 K. The latter appears as a result of spin canting within the antiferromagnetic core or is developed at some interfaces inside the nanoparticles. Considerable horizontal (HEB) and vertical (MShift) shifts of the magnetization hysteresis loops are observed after field cooli...