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In-plane Anisotropy in Hetero-Amorphous (CoFeB)-SiO2 Thin Films

Published online by Cambridge University Press:  11 February 2011

P. Johnsson ,
I. Aoqui ,
K. Nötzold ,
J. Allebert ,
M. Munakata  and
A. M. Grishin
P. Johnsson
Affiliation:
Department of Condensed Matter Physics, Royal Institute of Technology, Stockholm-Kista, S-164 40, SWEDEN
I. Aoqui
Affiliation:
Department of Applied Electrical Engineering & Computer Science, Sojo University, Kumamoto, 860–0082, JAPAN
K. Nötzold
Affiliation:
Department of Condensed Matter Physics, Royal Institute of Technology, Stockholm-Kista, S-164 40, SWEDEN
J. Allebert
Affiliation:
Department of Condensed Matter Physics, Royal Institute of Technology, Stockholm-Kista, S-164 40, SWEDEN
M. Munakata
Affiliation:
Energy Electronics Laboratory, Sojo University, Kumamoto, 860–0082, JAPAN
A. M. Grishin
Affiliation:
Department of Condensed Matter Physics, Royal Institute of Technology, Stockholm-Kista, S-164 40, SWEDEN
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Abstract

In order to engineer materials suitable for micromagnetic inductor cores we have fabricated and investigated the properties of granular (CoFeB)-SiO2 amorphous thin films. The deposition method, synchronous triple-rf magnetron sputtering onto rotating substrates, induces anisotropy in the film plane. Here we present magnetic hysteresis loops, resistivity and magnetoresistance measurements of two of these films, with different amount of metallic content. Both films have anisotropic resistivity, which is higher for the film with less metallic content. The low-metallic-content film exhibits typical isotropic giant magnetoresistance (GMR), while the film with higher metallic content shows a mixture of GMR and anisotropic magnetoresistance (AMR). The AMR appears at fields below 500 Oe. We believe that this has not been observed before in amorphous samples. The behaviour of the resistivity versus temperature ρ (T) indicates that the sample with lower metallic content consists of isolated grains while the high-metallic-content sample consists of a percolated network. Experimental ρ (T) data for the low-metallic-content sample fit: to the variable-range hopping model at temperatures lower than 221 K and can be described by excitation of the carriers to the mobility edge at higher temperatures.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 754: Symposium CC – Supercooled Liquids, Glass Transition and Bulk Metallic Glasses , 2002 , CC3.3
Copyright
Copyright © Materials Research Society 2003

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References

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