Deposition of Sub-micron Thick Sm-Co Magnetic
Films by Electron-Beam Evaporation
P. Saravanan1*, R. Vishnuraj1, 2, J. Arout Chelvane1, S.V. Kamat1
1
2
Defence Metallurgical Research Laboratory, Hyderabad 500058, India
Department of Nanoscience and Technology, Bharathiar University, Coimbatore 641 046, India
*
Corresponding author’s e-mail:psdrdo@gmail.com
Abstract
Sub-micron thick Sm-Co films with selective
phase composition such as Sm2Co17 and Sm2Co7 were
grown by electron-beam evaporation using appropriate
alloy ingots. A maximum coercivity, Hc of 1.48 kOe was
achieved for the 200-nm thick Sm-Co as-grown film
containing Sm2Co17 as a major phase; while 0.9 kOe was
obtained for the film of Sm2Co7-phase with similar
thickness.
Keywords: Magnetic thin films, Sm-Co, Electron-beam
evaporation, Micro-magnetic devices.
Introduction
Films of Sm-Co compounds find numerous
applications in micro-magnetic actuators, owing to their
excellent intrinsic and extrinsic magnetic properties [1,
2]. Over the past several years, sputtering has been used
for the deposition of Sm-Co films with useful hard
magnetic phases such as SmCo5, Sm2Co17 and Sm2Co7
[3]. However, this technique has a drawback of growing
thicker Sm-Co films, which is very much essential in
the device point of view. In this context, we herein
propose electron-beam evaporation as a potential means
to grow sub-micron thick Sm-Co films with selective
phase composition.
Experimental
Sm-Co films with thicknesses of 200 and 300nm were grown on Si (100) substrate by electron-beam
evaporation using two different alloy ingots: Sm4Co96
and Sm8Co92. These alloy ingots were prepared by
induction melting. Throughout the deposition, the
evaporation rate was maintained at 5 Å/s. 5 and 20-nm
thick Ta was used as a capping, as well as buffer layer.
The structural and magnetic properties of Sm-Co films
were investigated by XRD, FESEM and SQUID,
respectively.
Results and Discussion
The deposition of Sm-Co films with selective
phase composition using e-beam evaporation is often
difficult due to excessive evaporation of Sm. In this
work, this issue has been overcome by choosing
appropriate alloy targets containing lesser amount of Sm
(4 and 8 at.%). 200-nm thick Sm-Co films, which were
obtained with the Sm4Co96 ingot showed Sm2Co17 as a
major phase; while the films processed with the
Sm8Co92 ingot revealed Sm2Co7 as major constituent.
These observations are consistent with the roomtemperature SQUID magnetic measurements, in terms
of Hc variation. Hc of 1.48 kOe was estimated for our
Sm-Co films containing Sm2Co17-phase; while 0.9 kOe
was obtained for the film containing Sm2Co7-phase.
The Sm-Co phases observed in the 200-nm thick films
was also evident in the 300-nm thick film. However,
with increase in thickness, the Hc values tend to
decrease slightly.
Fig. 1: M-H curves for 200-nm thick Sm-Co films
obtained by electron beam evaporation using two
different alloy ingots (a) Sm4Co96 and (b) Sm8Co92.
Conclusion
The possibility of growing sub-micron thick
Sm-Co films with selective phase composition and
useful hard magnetic properties is demonstrated through
exploiting electron beam evaporation technique.
Acknowledgment
The keen interest shown by the Director,
DMRL, in this work is also gratefully acknowledged.
References
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