Size-dependent magnetism and exchange bias effect in Sm0.27Ca0.73MnO3 nanoparticles

• Published in: Journal of nanoparticle research : an interdisciplinary forum for nanoscale science and technology Vol. 15; no. 8
• Main Authors: Markovich, V., Puzniak, R., Fita, I., Mogilyansky, D., Wisniewski, A., Skourski, Y., Jung, G., Gorodetsky, G.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01-08-2013; Springer
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Equations of state, phase equilibria, and phase transitions; Exact sciences and technology; Inorganic Chemistry; Lasers; Magnetic properties and materials; Magnetic properties of nanostructures; Materials Science; Nanocrystalline materials; Nanoscale materials and structures: fabrication and characterization; Nanotechnology; Optical Devices; Optics; Photonics; Physical Chemistry; Physics; Research Paper; Small particles and nanoscale materials; Specific phase transitions; Structural transitions in nanoscale materials; Studies of specific magnetic materials; Nanocrystalline manganites; Magnetization; Exchange bias; Remanence; Temperature distribution; Order-disorder transformations; Particle size; Antiferromagnetic materials; Ferromagnetic materials; Magnetic hysteresis; Nanostructures; Heat treatments; Nanoparticles; Irreversible processes; Hysteresis loop; Asymmetry; Spin relaxation; Size effect; Coercive force; Ordering; Vitreous state; Nanostructured materials; Nanocrystal; Magnetic properties
• ISSN: 1388-0764; 1572-896X
• DOI: 10.1007/s11051-013-1862-4

Magnetic properties of compacted Sm
0.27
Ca
0.73
MnO
3
nanoparticles with average particle size ranging from 20 to 80 nm have been investigated in wide temperature and magnetic field range. It has been found that charge ordering transition gradually shifts to lower temperatures with decreasing particle size and almost disappears for 20 nm particles. At the same time, the relative volume of the ferromagnetic phase increases monotonously. Field-induced transition from antiferromagnetic to ferromagnetic state in 80 nm particles appears at the same magnetic field as in the bulk. In small 20 nm particles, the transition is strongly suppressed by increasing surface spins disorder. Magnetic hysteresis loops show size-dependent exchange bias effect with exchange field, remanence asymmetry, and magnetic coercivity that depend on cooling magnetic field and temperature. Magnetic training effect has been observed in 20 nm particles and analyzed using a spin relaxation model. The thermoremanence and isothermoremanence curves have provided fingerprints of irreversible magnetization originating from the glassy component. Analysis of remanence curves has showed that the inner core of small 20 nm particles behaves as a two-dimensional diluted antiferromagnet.