Physical signification of first-order reversal curves applied to various magnetic nanostructures

• Grant number: 08/08630-5
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: March 01, 2009
• End date: February 28, 2013
• Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics
• Principal Investigator: Marcelo Knobel
• Grantee: Fanny Béron
• Host Institution: Instituto de Física Gleb Wataghin (IFGW). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Associated research grant: 06/60440-0 - Study of strongly correlated systems in extreme conditions, AP.TEM

Abstract

The project main objective is to elaborate a framework of analysis of the results coming from the experimental measurements of the first-order reversal curves (FORC) of various magnetic nanostructures. Their integration in applications such as information storage, sensors, high frequency devices, etc. has shown promising advantages. To do so, these materials need to meet some precise specifications in terms of global properties, which are experimentally generally easily measured. However, knowing the individual magnetostatic properties of the nano-entities and their collective behavior is essential during the design of a device involving a nanostructure. We will extract this information from FORC results. It's a novel and easy to implement characterization technique which begins to spread out. For now, the results are usually only used as a fingerprint of the sample, without any quantitative interpretation of the magnetic processes that occurred. This can be explained by the non-uniqueness possible interpretations and by the deformations induced by internal and external interaction fields. These difficulties will be resolved by the systematic study of various nanostructured systems of increasing complexity: simple and core-shell nanoparticles, granular systems and ferromagnetic anti-dot arrays. In order to validate the interpretations done, the experimental measurements of FORC will be done in parallel to other magnetic characterization techniques, like ferromagnetic resonance and magnetoimpedance, and simulations of the magnetic behavior.