Overview of Materials Science Research
Hideaki Takayanagi
Materials Science Laboratory
The Materials Science Laboratory (MSL) aims
at discovering new quantum phenomena and
creating new concepts by producing new materials.
Toward these goals, the following five research
groups of MSL investigate various materials,
ranging from inorganic ones such as high-Tc
superconductors and photonic crystals to
organic materials like silicon polymers and
biopolymers. Another important feature of
MSL is the effective sharing of nanofabrication
and precise measurement techniques developed
originally in each group. This could possibly
open new fields in global information sharing
markets.
(1) Molecular Science Research Group
Research into high-luminescent optical devices
and new-functional electron devices using
new organic materials.
(2) Bio-Science Research Group
Research into information processing devices
using a novel architecture based on neural
function.
(3) Superconducting Thin Films research Group
Development of thin-film growth technology
for high-Tc superconductors using molecular
beam epitaxy method.
(4) Superconducting Quantum Physics Research
Group
Research into Andreev reflection in superconductor/semiconductor
junctions and macroscopic quantum coherence
in superconducting devices for the application
to q-bits.
(5) Nano-Structure Materials Research Group
Development of optical devices with unique
beam propagation using the fabrication technology
of three-dimensional photonic crystals.
Three major results obtained in fiscal year
1999 are reported in the following pages.
The first topic is about the control method
of the screw-pitch of herical polysilane
copolymers (Topic 1). We found that diarylpolysilylene
undergoes a reversible, thermo-driven helix-helix
transition with a transition temperature
of -10ßC. The obtained result could potentially
find application in a two state, switchable
material.
A new superconducting lead cuprate was prepared
by molecular beam epitaxy (MBE) method (Topic
2). A reduction of the synthesis temperature
in MBE makes it possible to synthesize a
thin film which can not be prepared by conventional
methods. Because the new cuprate contains
one CuO2 layer, it has critical temperature (Tc)
as low as 40 K. If we can synthesize this
lead cuprate with three CuO2 layers, Tc higher than 120 K is expected.
Ferromagnetism in semiconductor dot arrays
was theoretically predicted (Topic 3). Though
the dots do not contain any kind of magnetic
materials, the whole system shows ferromagnetism
by changing the number of electrons in the
dot. This controllability of magnetic states
can lead to the possibility of new magnetic
devices or switching ones.
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