Ornstein-Zernike correlations and magnetic ordering in nanostructures

ABSTRACT: In this paper we propose a Heisenberg variational approach to study pseudo-critical phenomena on ferromagnetic nanostructures. We combine a two-spin cluster 3-dimensional Heisenberg hamiltonian with Orstein-Zernike correlations and consider several geometries and crystalline lattices to explore the relationship among these factors and the effective number of nearest neighbors defined in several kind of nanometric structures. With this method we examine the size at which the pseudo-critical temperature of a magnetic nanoparticle reaches its bulk value. Our results shed light on the nanoscopic-microscopic limit, evidencing in particular that when one dimension is very small, independently of how big the other dimensions become, it is not possible for the structure to reach the bulk-like behavior. The results of our model are in good agreement with experimental data and other available analytical models.

• Autores: Mazo Zuluaga, Johan; Velásquez Sierra, Ever Alberto; Altbir, Dora; Mejía López, José
• Tipo de recurso: Article of investigation
• Fecha de publicación: 2014
• Institución: Universidad de Antioquia
• Repositorio: Repositorio UdeA
• Idioma: eng
• OAI Identifier: oai:bibliotecadigital.udea.edu.co:10495/30844
• Acceso en línea: https://hdl.handle.net/10495/30844
• Palabra clave: Fine-particle systems; Magnetic properties of nanostructures; sistemas de partículas finas; materiales nanocristalinos; Propiedades magnéticas de las nanoestructuras; Quantized spin models; Modelos de espín cuantificados
• Rights: openAccess
• License: http://creativecommons.org/licenses/by/2.5/co/