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Magnetoimpedance of Galvanostatically Electroplated Ni-Fe Permalloy Wires | IEEE Journals & Magazine | IEEE Xplore

Magnetoimpedance of Galvanostatically Electroplated Ni-Fe Permalloy Wires


Abstract:

We studied the magnetoimpedance of narrow Ni-Fe Permalloy wires prepared by electrodeposition. The wires were fabricated by lithographical patterning and chemical etching...Show More

Abstract:

We studied the magnetoimpedance of narrow Ni-Fe Permalloy wires prepared by electrodeposition. The wires were fabricated by lithographical patterning and chemical etching of electroplated thin films. The microstructure and magnetic property of the deposit were adjusted by using an organic additive added to the electrolyte. Aspect ratio of the wires was varied between 10 and 50 by changing the length of the wire while the thickness and width were fixed. The magnetoimpedance exhibited highest value at 30 MHz and was 18-25% depending on the aspect ratio. The magnetic fields for the highest magnetoresistance increased in proportion to the frequency in the range between 1 and 100 MHz.
Published in: IEEE Transactions on Magnetics ( Volume: 45, Issue: 6, June 2009)
Page(s): 2748 - 2749
Date of Publication: 19 May 2009

ISSN Information:


I. Introduction

Magnetoimpedance (MI) effect is the change of impedance in soft magnetic materials when we vary the magnitude of applied magnetic fields [1]–[3]. The origin of the phenomenon in the radio frequency (RF) range is the change of skin depth of the current applied to the specimen and is known to have a relation where is the frequency of the RF current and is the permeability of the material. MI effect has been mostly studied for possible applications to field sensing devices [4]. One of the most widely investigated types of soft magnets are those coated with Ni-Fe Permalloy thin films [5]–[7]. The most favorable property of Permalloy thin films for large MI effect is low coercivity [8]. Previous studies have shown that the grain size (L) of the thin film has a significant effect on ; specifically, for and for [9]. In an attempt to increase the change of MI in soft magnetic materials, we investigated the effect of organic additives on electroplated Ni-Fe Permalloy thin films and showed that their crystalline orientation, surface roughness, and could be adjusted by the species and concentration of the additives [10]. In particular, the reduction of Ni-Fe(200) in proportion to the concentration of the additives exhibited strong correlation with the decrease of and increase of MI [11]. Since MI effect arises from the motion of magnetization, magnetic anisotropy plays an important role in the magnitude of MI. Considering the shape anisotropy and miniaturization for possible application to a device, we fabricated thin wires of Ni-Fe Permalloy with varying aspect ratio and investigated the change of MI in the RF frequency range.

References

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