2. Materials structure physics

In the Department of Materials Structure Science, we are investigating the static structure of materials by means of precise X-ray crystal structural analysis, resonant X-ray scattering, magnetic X-ray scattering, and X-ray imaging. In addition, we are studying the dynamic structure of materials via a pump-and-probe experiment that uses a synchrotron radiation pulse. Our research has expanded from fundamental high-pressure properties to Earth and planetary science by a combination of high-pressure X-ray measurements. In addition to our research, we are optimizing beamlines and experimental devices to promote our research and are developing research methods that use the next-generation light source.

[Main research projects]

Elucidation of the mechanism of property expression using accurate structural analysis

External electric field and ion displacement in an “electronic ferroelectric” TTF-CA.(電場: Electric field, 変位: Displacement, 電子移動: Electron transfer)

We are studying how the arrangement of atoms, ions, and molecules in crystals contributes to property expression. In addition, we are studying the relationship between changes in the crystal structure and the physical properties of crystals when external perturbation, such as temperature, electric field, pressure, or photoirradiation, is added.

  • We discovered a new type of magnetic ordered phase in iron-based superconductors.
  • We found the vitreous state of electrons.
  • We demonstrated a new principle in the expression of electric polarization by using an organic ferroelectric.
  • We created a new technique of film-making by coating a semiconductor onto a surface that strongly sheds liquid.

Novel ordered phases as a stage of interesting physical properties

fig02.png Various novel ordered structures: orbital and spin-state ordering.

In materials science, novel ordered phases related to new physical properties are often found. Such phases are not only interesting as fundamental physics but are very important to understand the origin of physical property.

  • To elucidate the existence of the “intermediate spin state” in cobalt oxides
  • To fabricate new magnetic materials by controlling lattice strain with thinning

Study of physical properties under extreme conditions from high-pressure X-ray composite measurements and the inner structure of the Earth and planets

Using X-ray diffraction and composite measurements from a combination of absorption spectroscopy, transmission imaging, and Mössbauer scattering, we are studying extraordinary crystal structures and physical properties under extreme conditions created by using a very high-pressure apparatus, a cryogenic device, and a laser-heating device. The aim of these wide-ranging studies is:

fig03.png
  • To elucidate various structures of gas hydrates
  • To elucidate structure of silica glass deep in the Earth
  • To study inner structures of Jupiter and Pluto, which are made of water and gas
  • To elucidate structure and viscosity of magma in the Earth
  • To elucidate driving mechanism of mantle convection
  • To study behavior of iron in the Earth’s core and lower mantle
  • To study ultrahigh temperature and high-pressure synthesis of functional materials such as oxide superconductors and metal nitrides
  • To study the structural stability of basic elements and compounds under ultrahigh pressure

Materials science explored by X-ray imaging

fig04.pngfig05.png (Left) Optical devices: development of a phase retarder. (Right) IC tag reconstructed 3D image in a pearl nucleus.

We are developing various imaging systems to perform highly sensitive and highly accurate non destructive observations of the inner structures of electronic materials such as electronic devices. We hope to improve the performance of electronic devices by elucidating defects and strain fields in a sample by means of imaging. We are also developing an X-ray imaging method that can identify elements with high sensitivity.

Capturing photoinduced modifications in the structure and electronic state by a molecular movie

We are researching photoinduced modifications in the structure and electronic state by a molecular movie in optical functional materials, artificial photosynthesis systems, photocatalysts, and photoreactive proteins, and we are studying the mechanisms of the generation of those optical functions. We hope to develop new light energy conversion materials and ultrafast switching devices.

link1.gif The generation of a hidden phase in the photoinduced phase transition.
Cooperative structural change in the photoreactive protein.
link3.gif Photoinduced molecular magnetism and associated molecular structural modification.

Members

NamePosition Field
NAKAO, Hironori Assoc.Professor Condensed matter
KUMAI, Reiji Professor Condensed matter
MURAKAMI, Youichi Professor Condensed matter
KAWATA, Hiroshi Professor Condensed matter
ADACHI, Shinichi Professor Structural biology
ZHANG, Xiao-Wei Professor X-ray optics
KISHIMOTO, Shunji Assoc.Professor X-ray detector
HIRANO, Keiichi Assoc.Professor X-ray imaging
NOZAWA, Shunsuke Assoc.Professor Ultrafast Structural dynamics
KIKEGAWA, Takumi Assoc.Professor High pressure physics
SAGAYAMA, Hajime Assoc.Professor Condensed matter
ICHIYANAGI, Kouhei Assoc.Professor
IWANO, Kaoru Assoc.Professor Theory on condensed matter
SUGIYAMA, Hiroshi Assistant Prof. X-ray imaging
SAITO, Kotaro Assistant Prof.
KOBAYASHI, Kensuke Assistant Prof.

[Beamlines in charge]

X-ray crystal structure analysis/apparatus under extreaml conditions

BL-8A, BL-8B, BL-7C

High precision powder diffraction

BL-4B2

X-ray diffraction/scattering/detector development

BL-10A, BL-14A

X-ray diffraction experimental station

BL-3A, BL-4C, BL-6C, BL-18B

White X-ray magnetic diffraction experiments/X-ray optics

BL-3C

High pressure X-ray diffraction stations

BL-18C, AR-NE1A, AR-NE5C, AR-NE7A

A time-resolved X-ray station

AR-NW14A

X-ray imaging

BL-3C, BL-7C, BL-14B, BL-20B, AR-NE7A

[Links]

Condensed Matter Research Center http://cmrc.kek.jp/english/index_eng.html

Instrument R&D Team http://pfwww.kek.jp/KeisokuSystem/(Japanese only)