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Influence of reactive gases on the properties of CoFeZr-Alumina nanocomposites

Yury E. Kalinin 2Alexander V. Sitnikov 2Julia A. Fedotova 1Alexander K. Fedotov 1

1. Belarusian State University (BSU), F. Skaryna av. 4, Minsk 220050, Belarus
2. Voronezh State Technical University, Voronezh, Russian Federation


The influence of gas mixture during ion-beam sputtering on electric and properties of the films containing CoFeZr clusters embedded into alumina matrix has been investigated. The films with the fraction x of metallic alloy between 30 and 65 at.% were sputtered in the chamber evacuated either with pure Ar or in gas mixtures Ar + O2 and Ar + N2. It was revealed by Mössbauer spectroscopy, permeability, MFM and magnetization measurements that magnetic state of metallic nanoparticles at 300 K strongly depends on gas mixture in the sputtering chamber. In the samples deposited in pure argon CoFeZr nanoparticles displayed ferromagnetic state beyond the percolation threshold Xc = 40-45 at.% whereas at sputtering in Ar + O2 or Ar + N2 the Xc shifted to 50-55 at.% and the region of superparamagnetic state was expanded far beyond Xc. The last resulted in non-hysteresis behavior of magnetization curves and lowering of real and imaginary parts of magnetic permeability (m1 and m2 correspondingly) far beyond Xc in comparison with the films sputtered in Ar. Mössbauer spectroscopy have shown that such peculiarities were due to oxidation of nanoparticles preventing magnetic interaction and the direct electric contact between them. Note also that impedance of the samples studied displayed also appreciable inductive contribution at intermediate frequences 1-100 kHz.


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Presentation: Poster at E-MRS Fall Meeting 2006, Symposium A, by Alexander K. Fedotov
See On-line Journal of E-MRS Fall Meeting 2006

Submitted: 2006-05-12 16:26
Revised:   2009-06-07 00:44