Eur. Phys. J. B 46, 471-474 (2005)
https://doi.org/10.1140/epjb/e2005-00276-2

Synthesis and magnetic properties of FeNi₃/Al₂O₃ core-shell nanocomposites

National Laboratory of Solid State Microstructures, Physics Department, Nanjing University, Nanjing 210093, P.R. China

Corresponding author: ^a wzhong@netra.nju.edu.cn

Received: 14 January 2005
Revised: 21 May 2005
Published online: 7 September 2005

Abstract

In this study, FeNi₃/Al₂O₃ core-shell nanocomposites, where individual FeNi₃ nanoparticles were coated with a thin layer of alumina, were fabricated by a modified sol-gel method. Several physical characterizations were performed on the samples of FeNi₃/Al₂O₃ nanocomposites with different thickness of Al₂O₃ shell. The encapsulation of FeNi₃ nanoparticles with alumina stops FeNi₃ agglomeration during heat treatment, and prevents interaction among the closely spaced magnetic FeNi₃ nanoparticles. The Al₂O₃ insulating shell improves the soft magnetic properties of FeNi₃. The study of the complex permeability of the samples shows that the real part µ' of the permeability of the sample with Al molar content of 20% (Al/(Fe+Ni)) is as high as 12, and independent of frequency up to at least 1 GHz. The tunneling magnetoresistance arising from the presence of the Al₂O₃ shell have also been studied.