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Alexei Sozinov, Alexander Likhachev, Nataliya Lanska, and Kari Ullakko
answer a
few questions about this month's fast breaking paper in the field of
Physics.
From
•>>October 2003
Field:
Physics
Article Title: Giant magnetic-field-induced strain in NiMnGa seven-layered martensitic phase
Authors: Sozinov, A;Likhachev, AA;Lanska, N;Ullakko, K
Journal: APPL PHYS LETT
Volume: 80
Page: 1746-1748
Year: MAR 11 2002
* Helsinki Univ Technol, POB 6200, FIN-02015 Espoo, Finland.
* Helsinki Univ Technol, FIN-02015 Espoo, Finland.
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 Why
do you think your paper is highly cited?
We are very pleased to be named as the authors of a Fast
Breaking Paper in the field of Physics and we can suggest a few
reasons for this attention. The approximately 10% magnetic
field-induced strain (MFIS) reported in the paper is the maximal
value observed at the moment. It was the first observation of
MFIS in an orthorhombic phase (so far MFIS has been observed in
different materials with tetragonal crystal structure).
Additional extended experimental data and
theoretical considerations supporting our paper have been
presented in detail at various international conferences and
meetings.
Does
it describe a new discovery or a new methodology that's useful to
others?
In the last few years, several research groups have succeeded
in the observation and detailed investigation of 6%
magneto-strain effect in some non-stoichiometric Ni2MnGa-based
alloys. We have found that one of the known martensitic phases in the same Ni-Mn-Ga system possess one key similar property — a really giant strain response of 10% in a moderate magnetic field of less then 1
Tesla. We have also presented some physical
properties of this phase, which are important for MFIS
observation but were never measured before. We can expect that
our results will be a help to other researchers in dealing with
the new promising magnetic shape memory alloy systems—including
Ni-Mn-Al, Fe-Pd, Fe-Pt, Co-Ni-Al, Co-Ni-Ga, Ni-Ga-Fe, and
others.
Could
you summarize the significance of your paper in layman's terms?
Magnetic shape memory materials are expected to have a high
potential in practical applications. The physical mechanism of a
giant magnetic field-induced strain observed in those materials
is based on a crystallographic domain (twin variants)
reorientation under an applied magnetic field connected with a
high magnetic anisotropy of low symmetry martensitic phase and
also a high mobility of twin boundaries. Several ferromagnetic
materials exhibiting this large magnetic-field-induced strain
have been found in recent year s.
We added to this field new material with the highest (at the
moment) magnetic field-induced strain and tested a basic
theoretical understanding of this phenomenon.
How
did you become involved in this research?
In 1996, Kari Ullakko discovered large magnetic-field-induced
strain 0.2% for the first time. In 1999 he had obtained funding
from the National Technology Agency of Finland (Tekes) and
invited Alexei Sozinov, Alexander A. Likhachev, and Nataliya
Lanska to continue the research. It was a new and exiting field
for all of us.
Alexei Sozinov, Ph.D.
Laboratory of Physical Metallurgy and Materials Science
Helsinki University of Technology, Finland
Alexander A. Likhachev, Ph.D.
Laboratory of Biomedical Engineering
Helsinki University of Technology, Finland
Nataliya Lanska, M. Sc.
Laboratory of Biomedical Engineering
Helsinki University of Technology, Finland
Kari Ullakko, Ph.D.
Laboratory of Biomedical Engineering
Helsinki University of Technology, Finland
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ESI Special Topics,
October 2003
Citing URL - http://www.esi-topics.com/fbp/2003/october03-Sozinov-physics.html
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