Superparamagnetic doped lanthanum manganet for
switching applications
K. Thyagarajan1, G.K. Sivasankara Yadav1*, Daruka Prasad B2, H. Nagabhushana3
1
Department of Physics, JNTUA College of Engineering, Pulivendula 516 390, India
Department of Physics, B.M.S. Institute of Technology, Avalahalli, Bangalore- 560 064.
3
Prof. C.N.R.Rao Centre for Advanced Materials, Tumkur University, Tumkur 572 103, India
2
Corresponding author’s e-mail:ktrjntu@gmail.com, Tel.: +91-9440874936.
*
Abstract
The series of lanthanum manganet were prepared by
Sonochemical and solid state reaction techniques for
nano and bulk samples with Ba as a dopant. The prepared
samples were characterized and their magnetic properties
of the materials measured by using VSM shows excellent
superparamagnetic behavior with the dopants. Hence the
prepared materials may be useful for fast switching
applications.
Keywords: Lanthanum manganets, soft magnets,
superparamagnetism, Sonochemical technique, switching
devices.
Introduction
The perovskite-type manganate materials have raised a
strong interest in their versatile electronic and magnetic
properties [1]. Most of these materials are rare earth
(RE) doped manganates with the general formula
REMnO3, that are doped on the A-site with lower
valent cations, such as Ca2+, Sr2+ or Ba2+ .
Depending on the RE element, as well as on the nature
and the amount of the dopant the materials exhibit a
great variety of structural, electrical and magnetic
properties [2]. This leads to fascinating effects such as
spin-polarized transport, a magnetic field induced
insulator-to metal transition, and multiferroicity. It also
gives rise to a variety of possible applications of the as
functional materials for magnetic sensors, read-write
heads for hard drives, spintronics etc [3, 4]. In this
paper we are reporting the synthesis of doped lanthanum
manganets with divalent cations and their magnetic
properties
measured
using
vibrating
sample
magnetometer (VSM).
constant temperature of 120°C for 24 h. The residues
are formed in the bottom of the beaker and collected.
This black material and calcinated at 500°C for 2 h. The
bulk sample was prepared by using solid state reaction
method.
Magnetic Studies
The intrinsic magnetic properties like saturation
magnetization (Ms), remanance (Mr) and coercivity
(Hc), with different concentration and for bulk and nano
size materials were studied using M-H loops at room
temperature. The Ms and Mr values observed were
maximum for nanosize compound than its bulk
counterpart. The bulk material shows paramagnetic
behavior but nanosize compound shows the perfect
superparamagnetic behavior with almost zero
coercivity.
From the microstructure analysis, the
coercivity Hc is dependent on grain size. The deviation
from linear relationship for Hc and porosity can be
related to the variation of exchange interaction, the
magnetic moments and the redistribution of cations.
Each loop is clearly showing low coercivity for each of
the composition, indicating that all the samples belong
to the family of soft ferrites.
Synthesis method
Manganese carbonate was sonicated in diluted
nitric acid for 20 min to convert in to the insoluble
carbonate in to soluble nitrate. A high tense sonication
was carried out with high intensity titanium horn
operated at a frequency of 20 KHz (Sonics, USA).
Calcium carbonate and Barium carbonate were added in
a three steps with 15 min duration to the manganese
solution during the sonication process. Finally
Lanthanum nitrate solution is added to the above mixed
solution in three steps. After sonication process the
solution was allowed to dry in the Hot air oven at a
Fig. 1: Magnetic properties of LaBaCaMnO3 bulk and
nanopowders.
Conclusion
The prepared perovskite manganite shows excellent
superparamagnetic behavior with considerable value of
saturation magnetization and zero coercivity.
Acknowledgment
The authors would like to acknowledge the SAIF, IIT,
Madras for providing the facilities of magnetic
measurements (VSM).
References
[1] J. H. Wang, J. L. Sun, C. R. He, Q. Wang, W. G.
Wang, “Mass synthesis of high performance
(La0.75Sr0.25)0.95MnO3 nano-powder prepared via a
low-carbon chemical solution method”, J. Power
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[2] J. Im, I. Park, D. Shin, “Preparation of nanocrystalline strontium-doped lanthanum manganite
(LSM) powder and porous film by aerosol flame
deposition”, Ceramic Internationa, 40, 4 (2014), 5567 –
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[3] H. Okuyucu, H. Cinici, T. Konak, “Coating of nanosized ionically conductive Sr and Ca doped LaMnO 3
films by sol-gel route”, Ceramic International, 39, 2,
(2013) 903 – 909.
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“Manufacture of a non-stoichiometeric LSM cathode
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