Magnetoimpedance Study on Co69Fe7Si14B10
Multilayer at Low Frequencies
N V S S Seshagiri Rao and V. Satya Narayana Murthy*
Department of Physics, Birla Institute of Technology & Sciences – Pilani, Hyderabad campus, INDIA
*
Corresponding author’s e-mail: satyam@hyderabad.bits-pilani.ac.in
Tel.: +91-40- 66303583; Fax: +91-40-66303998
Abstract
Magnetoimpedance effect has been studied for the
Co69Fe7Si14B10 / Cu / Co69Fe7Si14B10 film with layer
thickness of 100 nm / 10nm / 100nm. GMI has a side effect
of the skin effect which depends on the particular magnetic
structure
and
frequency.
In
addition
to
magnetoimpedance,
magnetoresistance
and
magnetoinductance have been studied at frequencies below
1 MHz for Co69 Fe7 Si14 B10 multilayers.
Keywords: Magnetoimpedance, Magnetoresistance,
Magnetoinductance, Skin effect, Soft magnetic materials,
Magnetic multilayers.
sputtering unit. Films of 7 mm x 7 mm dimensions are
used for the measurements. Impedance, resistance and
inductance of the multilayers were measured using
Waynee’s Kerr LCR meter up to a frequency of 1 MHz.
DC magnetic field 0 -100 Oe was applied using a
Helmholtz coil.
Fig. 1 shows a variation of MI, MR and mi at
500 kHz for the as deposited multilayer. Maximum
values of 7%, 7% and 14% were observed for MI, MR
and mi respectively. At high frequencies decrease in
values were observed.
Introduction
Impedance is a complex quantity, Z = R + jX.
Hence the variation of GMI consists of variation of the
real (R) and imaginary (X) quantities with respect to
field and their variation is called magnetoresistance
(MR) and magnetoinductance (mi) [4]. Depending on
the frequency of the applied signal GMI effect is
dominated by either MR or mi. In this paper we are
presenting the variation of MI, MR and mi for
Co69Fe7Si14B10 multilayer.
Co69Fe7Si14B10 / Cu / Co69Fe7Si14B10 film with
layer thickness of 100 nm / 10nm / 100nm were
deposited on glass substrate using DC magnetron
16
500 kHz
mi
MR
MI
12
Ratio
The Giant Magneto impedance (GMI) dates
from 1994 [1-4]. GMI effect consists of a large
variation of the impedance of metallic magnetic
conductor when submitted to the action of DC magnetic
field.
Its origin is related to the classical
electromagnetic skin effect. When High frequency
current flows along the length of the sample, the current
is constrained to flow at surface. This penetration depth
known as skin effect, according to classical theory is
inversely proportional to the conductivity, permeability
of the sample and frequency of the ac current. The skin
effect has been conventionally studied in metallic
conductors with high electrical conductivity so,
elements like Cu, Au, or Ag exhibit noticeable skin
effect.
8
4
0
-100 -80
-60
-40
-20
0
20
40
60
80
100
Magnetic field (Oe)
Fig. 1: Variation of MI, MR and mi at 500 kHz
Acknowledgment
The authors acknowledge Department of
Science and Technology, India for financial support for
the above work.
References
[1] R.S.Beach, A.E.Berkowitz, Appl.phys.Lett. 64
(1994) 3652.
[2] R. S.Beach, A.E.Berkowitz, J.Appl.phys.Lett. 76
(1994) 6209.
[3] G. V. Kurlyandskaya, et. al. J.Appl.phys.Lett. 107
(2010) 09C502.
[4] V. Satya Narayana Murthy, G. Markandeyulu
J.Magn Magn Matter 310 (2007) e669.