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Structure and electrical properties of the film CoFeZr-aluminium oxide nanocomposites

A. V. Mazanik 1Yu. E. Kalinin 3A. K. Fedotov 1J. A. Fedotova 1Sylwia Wrotek 2A. V. Sitnikov 1I. A. Svito 1S. V. Gusakova 1

1. Belarusian State University (BSU), F. Skaryna av. 4, Minsk 220050, Belarus
2. Polish Academy of Sciences, Institute of Physics, al. Lotników 32/46, Warszawa 02-668, Poland
3. Voronezh State Technical University, Voronezh, Russian Federation


The goal of present paper was to investigate the influence of phase composition on DC and AC conductance of film composites containing CoFeZr nanoparticles (6 to 10 nm dimensions) in aluminium oxide matrix for atomic concentrations of metallic fraction x = 30-65 %.
Mössbauer study are evident of strong correlation between metallic fraction x in the composite and relative contribution of Fe ions in two different valence states (2- and 3-multiple-charged). It probably shows that phase composition of metallic component depends on the ratio between metallic and dielectric components. Temperature dependencies of DC resistivity described by exponential laws are characteristic for variable range hopping with Mott or Shklowski-Efros mechanisms. In the temperature range 77-300 K static I-V characteristics of the samples displayed non-ohmic character and were attributed to co-existence of Pole-Frenkel and ohmic (linear) laws. In so doing, the exponential contribution increased with the elevation of dielectric component. It was also exhibited negative magnetoresistance effect with squared-like magnetic field dependence that can be ascribed to tunneling of carriers between metallic particles.
Both real and imaginary parts of impedance in high-ohmic samples with x < 40 % in the frequency range from 0.1 to 10 kHz were not dependent on applied bias voltage, at least, for electric fields up to 4 V/cm. In the samples with x > 40 % the dramatic increase (up to 2-3 orders of magnitude) of capacitance modulus occurs at achieving some threshold value of bias voltage. The obtained increase of capacitance modulus with bias voltage is always accompanied by the decrease of real part of impedance. The value of threshold bias voltage decreases with the growth of metallic component content in the studied composites.


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Presentation: poster at E-MRS Fall Meeting 2004, Symposium I, by Sylwia Wrotek
See On-line Journal of E-MRS Fall Meeting 2004

Submitted: 2004-05-14 15:44
Revised:   2009-06-08 12:55