Monte Carlo study of the magnetic properties of frozen and non-interacting nanoparticles

Author(s)

Arantes, Fabiana R. ^[1] ; Cornejo, Daniel R. ^[1]

Affiliation

^[1] Univ Sao Paulo, Inst Fis, BR-05508090 Sao Paulo - Brazil

• Document type: Journal article
• Source: JOURNAL OF NANOPARTICLE RESEARCH; v. 15, n. 9 SEP 2013.
• Web of Science Citations: 0

Abstract

The transition from the blocked to the superparamagnetic regime in non-interacting and frozen magnetite nanoparticles with diameters of about 10 nm was studied using the Monte Carlo method with the Metropolis algorithm. The behavior of the blocking temperature (T-B) was analyzed for different nanoparticle systems. For ensembles of homogeneous nanoparticles, T-B showed a linear dependence on the exchange constant, which is the main factor that determines T-B. Comparatively, the dependence of T-B on the magnetocrystalline anisotropy constant was much weaker and nonlinear. It was observed that T-B decreases with the decreasing particle size following a finite-size scaling theory. Systems of nanoparticles with a core/dead-layer structure exhibited a lower T-B than the corresponding homogeneous nanoparticles. It was verified that the presence of a thin, hard layer on the nanoparticles surface, where the exchange interaction was improved, produced a significant increase in the blocking temperature. (AU)

• FAPESP's process: 10/01655-2 - Systems of magnetic nanoparticles: experimental studies and Monte Carlo simulations
• Grantee: Fabiana Rodrigues Arantes
• Support Opportunities: Scholarships in Brazil - Doctorate