Synthesis and Characterization of Highly Ordered
NiFe/Cu Multilayer Nanowires
Monika Sharma1*, Bijoy K. Kuanr2, and Ananjan Basu3
1
Cente for Applied Research in Electronics, Indian Institute of Technology Delhi, India
2
Special Centre for Nanoscience, Jawaharlal Nehru University, New Delhi, India
*
Corresponding author’s e-mail:monikasharma1604@gmail.com, Tel.: +91-9560711488
Arrays of NiFe/Cu multilayer nanowires were fabricated by
electrodeposition into porous anodic alumina templates
(pore diameter = 200 nm and interwire spacing = 300 nm),
with NiFe disc segment between 150 to 350 nm, and a Cu
thickness between 15 to 100 nm. By controlling the
deposition conditions such as time, pH, concentration,
potential, we varied the microstructures of multilayer
nanowire arrays. The characterization was performed by
transmission electron microscopy (TEM) for topology of
multilayers, X-ray diffraction (XRD) for structural
analysis, and superconducting quantum interference
(SQUID) for static magnetic behavior. These structures
have potential applications in future nanodevices.
Keywords: Electrodeposition, multilayer, nanowires,
hysteresis curves, anodic alumina template.
Introduction
Multilayer
nanowires
(magnetic/non-magnetic
segments) are promising candidates for future
nanodevices, especially for the application of spintronics,
and logic devices [1]. In recent years, researchers are
interested to investigate the interlayer coupling
interactions which can influence the device properties.
Nanowire fabrication by electrodeposition based on
template approach is a powerful and flexible tool adopted
to fabricate a variety of multilayer nanowires (MLNWs).
Their magnetic behavior depends upon a number of
factors, mainly: nanowire diameter, length and interwire
distance, disc thickness, and ferromagnetic material.
respectively as shown in the cyclic voltammetry and
chronoamperometry curves in Fig. 1(A). We characterize
these multilayer nanowires by TEM, XRD, and SQUID
techniques.
Results and discussion
The morphology of the multilayer nanowires were
analysed using TEM [Fig. 1(B)] which reveals the
diameter of nanowires to be 200 nm. In sample B the
thickness tm is 350 nm and tnm is 35 nm. The X-ray
diffraction spectrum confirms a strong (111) texture with
other peaks at (200) and (220). Magnetic measurements
were done using SQUID, which gives the hysteresis
loops when the field is applied perpendicular and parallel
to the axes of MLNWs as shown in Fig. 2. The saturation
field for both orientations are same as the aspect ratio of
the disk is small. The coercivity along the parallel
orientation is 80 Oe whereas it is 44 Oe along
perpendicular orientation.
0.04
0.0
CA
CV
(A)
(B)
0.02
Current (A)
Abstract
-0.5
0.00
-0.02
-1.0
-0.04
0
50
100
150
200
-1.5 100 nm
250
Time (sec)
Fig. 1: (A) Deposition spectrum for multilayer NWs, (B) TEM image
of NiFe/Cu multilayer
Experimental
NiFe/Cu Multilayer
0.007
Long Moment (emu)
We report here the fabrication of multilayer [NiFe/Cu]N
nanowire arrays by electrodeposition technique. The
thickness of magnetic and non-magnetic segments are
controlled during deposition. Three samples were
investigated in this study: A-[NiFe150/Cu15]50, B[NiFe350/Cu35]50, C-[NiFe250/Cu100]50, where they are
labelled as [NiFetm/Cutnm]N; N being number of layers, tm
and tnm being thickness of magnetic and non-magnetic
segments in nm respectively. Three electrode system is
used for electrodeposition as reported in earlier works
[2]. A single electrolyte bath consisting of appropriate
amount of NiSO4, FeSO4, CuSO4 and H3BO3 were used
as electrolysis. The deposition potential was switched
between -1.4V to -0.3V for Py and Cu layers growth
Parallel axis
Perpendicular axis
0.000
-0.007
-5
-4
-3
-2
-1
0
1
2
3
4
5
Magnetic Field (kOe)
Fig. 2 Hysteresis loop of sample B with the magnetic field applied
parallel and perpendicular to the axes of NWs
References
[1] J. Yoon et al., Applied Physics Express, vol. 4, (2011), pp.
063006.
[2] M. Sharma et al., IEEE Transaction on Magnetics,
DOI:10.1109/TMAG.2013.2287223