Research
Ferroic materials and multiscale phenomena
A highly
interdisciplinary research field
Classification
of ferroic materials
Ferroic Materials and Multiscale Phenomena
A huge class of materials exhibits spontaneous (automatic) order with
respect to atomic/ionic displacement or spin below a characteristic temperature
(Currie temperature); they are called ferroic materials. Such ordering
transitions (called ferroic transition) result in very interesting phenomena at
three different length scales simultaneously, from atomic/nano scale (atomic/ionic displacement, spin, etc.),
mesoscopic scale (domain), to macroscopic scale (strain, electric effects,
magnetic effects). The ferroic transitions and
the associated multiscale phenomena, as typical examples of cooperative and
self-organization phenomena, are not only of significant scientific interest
but also of profound technological importance. Typical examples of important
properties of ferroic materials include, but not restricted to, shape memory
effect, superelasticity, pyroelectric effect, piezoelectric effect, huge
mechanical, electrical and magnetic susceptibility, permanent magnetism and
magnetostriction. Ferroic materials play an indispensable role in our modern
society as major functional materials, and are expected to gain their
importance in our electronic and information age in which conversion of
different forms of energy (mechanical, electrical, magnetic, etc) is crucial.
A highly interdisciplinary research field
Traditionally, different kinds of ferroic materials (see classification of ferroic materials) were the
subjects for different scientific communities. Metallurgists studied
ferroelastic/martensitic alloys; ceramicists studied ferroelectric materials,
whereas physicists studied ferromagnetic and superconductive materials.
However, in recent years it has been gradually realized that fundamental
physics in these apparently different groups of material bears striking
similarity or analogy, and knowledge obtained in one group of materials can be
applied to understanding parallel physical phenomena in other groups.
Therefore, it is important to study different groups of ferroic material by an
interdisciplinary approach.
Classification
of Ferroic Materials
1.
Ferroelastic/martensitic materials
multiscale phenomena: atomic displacement, domain, shape change, shape memory,
superelasticity, high damping capacity, etc.
2.
Ferroelectric materials
multiscale phenomena: ionic displacement/polarization, ferroelectric domain,
electric charge, pyroelectricity, etc.
3.
Ferromagnetic materials
multiscale phenomena: spin alignment, magnetic domain, magnetism, etc.
4.
Hybrid ferroic materials (Ferroelasto-ferroelectric
materials, ferroelasto-ferromagnetic materials, etc. …)
Many ferroic materials belong to this group and they are characterized by
coupling among strain, electric polarization and magnetism. Such coupling can
result in very interesting multiple response in strain, electric charge and
magnetism, and are important for actuator and energy converter applications.
Typical examples are piezoelectric effect, magnetostriction, and so on.
5.
Non-conventional ferroic materials (HTc
superconductors, some BCS superconductors, giant magnetoresistive materials)
In these materials, the interplay among dynamic strain (phonon), magnetism, and
electrons plays an essential role in the abnormal physical properties. Such
interaction is also an important topic in modern condensed matter physics.
Aim of Our Program
- Explore
physics of ferroic transition and associated multiscale phenomena by an
interdisciplinary approach.
- Explore and
discover novel properties in ferroic materials and help to develop new
functional materials.
Current Research Topics
１．
Ferroelectrics and in particular Pb-free
piezoelectrics with superior performance.
２．
Role of point defects in ferroelectric,
ferromagnetic, and ferroelastic/martensitic materials and the associated novel
effects.
３．
Glass phenomena in ferroic systems and the
associated novel effects.
４．
Ferroic domains and their relation to physical
properties of ferroic materials.
５．
Computer simulations of ferroic transitions and
associated effects.
６．
Relaxation phenomena in ferroic materials.
We welcome excellent people with background in related field to join us as JSPS fellow or NIMS fellow