Stoichiometry Dependence on the Diameter of La2/3Ca1/3MnO3 Manganite Nanoparticles

• Published in: Journal of superconductivity and novel magnetism Vol. 25; no. 5; pp. 1611 - 1617
• Main Authors: Restrepo-Parra, E., Orozco-Hernández, G., Riaño-Rojas, J. C.
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.07.2012; Springer
• Subjects: Anisotropy; Characterization and Evaluation of Materials; Computer simulation; Condensed Matter Physics; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Ferromagnetism; Magnetic Materials; Magnetic properties; Magnetic properties and materials; Magnetic properties of nanostructures; Magnetism; Magnetotransport phenomena, materials for magnetotransport; Manganites; Monte Carlo methods; Nanoparticles; Original Paper; Physics; Physics and Astronomy; Strongly Correlated Systems; Superconductivity; Three dimensional; Stoichiometry; Monte Carlo; Heisenberg; Magnetic nanoparticles; Curie temperature; Metropolis algorithm; Particle size; Curie point; Magnetization; Core shell structure; Heisenberg model; Magnetic nanomaterial; Nanoparticles; Spin dynamics; Monte Carlo methods; Magnetic particles; Anisotropy; Hamiltonians; Classical theory; Ferromagnetic-paramagnetic transitions; Manganites
• ISSN: 1557-1939; 1557-1947
• DOI: 10.1007/s10948-012-1489-1

This study presents the magnetic properties of manganite fine particles using Monte Carlo simulations in the framework of a core–shell model. A single-spin movement Metropolis dynamics was implemented to compute equilibrium averages. Calculations were performed on the basis of a three-dimensional classical Heisenberg Hamiltonian, involving the presence of Mn 3+ ( and ) and Mn 4+ ( ) cations, and their nearest neighbor interaction. The Hamiltonian includes a surface anisotropy term applied to surface ions, and cubic anisotropy for ions belonging to the core. Different diameters were considered in order to figure out different off-stoichiometric scenarios and the influence on the magnetic properties. Results reveal a well-defined linear particle size inverse dependence of the Curie temperature. No evidence for surface spin disorder was detected. Finally, susceptibility data reveal that the ferromagnetic-to-paramagnetic transition occurs in a gradual fashion ascribed to a differentiated behavior between the core and surface. Initially, the surface contribution to magnetic properties is high; as the nanoparticle size increases, the core contribution becomes stronger.