Characterization of (Co_0.45Fe_0.45Zr_0.10)_x(Al₂O₃)_1–x nanocomposite films applicable as spintronic materials

Abstract

The combined use of scanning electron microscopy, Mössbauer spectrometry, X‐ray diffraction and also DC/AC electrical and magnetic characterization techniques allowed this work to elucidate the influence of metal‐to‐dielectric component ration, and effect of oxygen in gas mixture on phase structure and properties of the Co0.45Fe0.45Zr0.10 ferromagnetic nanoparticles in amorphous dielectric Al2O3 matrix. The films of 3–5 µm thickness with compositions of 30 at.% < X < 60 at.% were sputtered on a single substrate from the compound target in the chamber containing either pure Ar or Ar‐O gas mixture. The films sputtered in Ar‐O mixture resulted in partial oxidation of metallic nanoparticles causing the shift of percolation threshold X c to 55 at.% as compared to 45–47 at.% for the samples deposited in pure Ar. Mössbauer studies of the films sputtered in Ar gas have shown that at X < X c metallic nanoparticles were at superparamagnetic state but for X > X c metallic phase showed a ferromagnetic behavior. DC carrier transport at the temperatures of 77–350 K were explained by hopping mechanisms and described by Mott and Shklowski‐Efros laws. That was also confirmed by the relationship power law of Z ′(f ) ∼ f –s (s ≤ 2) for real part of impedance at low temperatures (<120 K) for the samples on dielectric side of MIT. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Formation of Noncoil-Like Inductance in Nanocomposites (Fe0.45Co0.45Zr0.10)x(Al2O3)1-xManufactured by Ion-Beam Sputtering of Complex Targets in Ar+O2Atmosphere

“…All the technological procedures and experimental techniques are described in [1,2,[4][5][6][7][8][9]. The method used allows for manufacturing of samples with different metallic phase concentrations 0.313 < x < 0.621 under the identical deposition conditions.…”

The Features of Real Part of Admittance in the Nanocomposites (Fe45Co45Zr10)x(Al2O3)100 - xManufactured by the Ion-Beam Sputtering Technique with Ar Ions

“…2, curves 2, 3, 4, in the form of the normalized dependences σ(d)/σ(x = 100 at.%). As can be seen, this dependence is very well approximated by formula (2), that allows to extract the values of α H which are estimated as 1.06 ± 0.25 nm −1 for D between 6 and 10 nm. The conducted analysis confirms the presence of hopping conductance in the samples studied with x < x C .…”

“…All the technological procedures and experimental techniques are described in [2][3][4]. The used method makes it possible to obtain a variety of samples under identical conditions but with different metallic phase concentrations ranging 30 at.% < x < 65 at.%.…”

“…Our AC conductivity measurements were carried out with the same samples as for the measurements of direct current (DC) conductance, phase composition and magnetic state described in [2][3][4]. The previous measurements showed that the x C value was close to 45-47 at.% [2].…”

“…Also, it should be noted that the majority of the electric, magnetic, and other properties of such binary nanocomposites are mostly influenced by the external effects just at x values approaching the percolation threshold x C [2][3][4]. This feature makes these nanocomposites very attractive to the producers of various sensors, detectors, etc.…”