Takafumi MIYANAGA


Department of Advanced Physics,  Professor


1960 born
1983 Kanazawa University (B.Tech)
1985 Kanazawa University (Ms.Tech)
1988 Osaka University (Dr.Sc)
1988 Hirosaki University (Assistant professor, Department of Physics)
1990-91 Simon Fraser University, visiting professor (Department of Physics)
1997 Hirosaki University (Associate Professor, Department of Materials Science and Technology)
2003 Hirosaki University (Professor, Department of Materials Science and Technology)
2006 Hirosaki University (Professor, Department of Advanced Physics)


Room:0702
Phone:0172-39-3551
FAX:0172-39-3551


e-mail: takaf@cc.hirosaki-u.ac.jp


in Japanese


Se non e vero, e bene trovato

Research Interests:

·  Condensed Matter Physics / Materials Science

·  Structural Dynamics (Phase Transitions, Chemical Reactions, Surface Processes, Nonequilibrium states) , XAFS / Synchrotron Radiation

 

XAFS (X-ray Absorption Fine Structure) studies on structurally disordered materials:
XAFS is a new method for structural analyses by using the synchrotron radiation source. This is a special technique for the local structure because of the short mean free path of the photoelectron. XAFS is applied to disordered systems (glass transition and semiconductor to metal transitions in amorphous and liquid As-Te and Se-Te systems) .

Quantum Statistical Calculations for Debye-Waller Factor in XAFS, EELS and ARXPS (Photoelectron Diffraction):
Thermal factors or Debye-Waller factors in the X-ray spectroscopy are calculated from the framework of field theoretical method and path integral approaches.

Structure and Dynamics of hevey fermion superconductors:

Cumulant analyses reveal the dynamics of the atom located in the double-well potential.  Lattling mechanism is important for the origin of the superconducting phenomenon in PrOs
4Sb12.  EXAFS can investigate directly such a dynamics of Lattling atoms.

Magnetic XAFS (X-ray Magnetic Circular Dichroism):
Using circular polarized X-ray from the synchrotron radiation, we can detect the local magnetic structures in the magnetic materials. XMCD is powerful for disordered alloys, i.e. Ni-Mn alloys, in which atomic local order is important for magnetic structure, and nano structural magnetic thin films.

Nanometer-Scale Science and Technology:
XAFS studies on Thin Films and Mesoscopic Systems: Local structure of the active thin layers in green and blue LED (InGaN single and multiple-quantum-wells) by fluorescence XAFS using multi-element SSD.  Ag thin film and fine particles deposited on Si single crystal studied by total conversion electron XAFS.  The formation process of the Ag nano-clusters in the cavity of the zeolites is studied by in-situ XAFS meaurements.  Core/Shell nano particle and its structre studied by XAFS.

Structural Phase Transition in Perovskite Ferroelectric Materials:
Some Perovskites materials show the ferroelectricity and undergo the structural phase transitions. XAFS reveals the mechanism of the structural phase transition from the local point of view, which is complementary information from difraction techniques by X-ray and neutrons.  Landau theory of phase transition.

Chemical Physics/Soft Matters:
Quantum effect in the chemical reaction rate is calculated from the path-integral approach.  The relation between the ligand exchange reaction rate constant and XAFS thermal factor can be analyzed from the view point of anharmonic potential.  Pattern formation in the complex systems; The formation process of Konfeitos and snow road in winter.

XAFS for Coordination Chemistry/Environmental:
Various 3d metal complexes, battery materials, the materials in environmentals and Lanthnoid organometallic compounds were analyzed by using XAFS.


 

Students

Alumni

Visiting Researchers

  • Paolo Fornasini (Trento, Italy) 2006
  • Anton V. Ryazhkin (Ekaterinburg, Russia) 2004, 2000
  • Arvind Agarwal (Allahabad, India) 2003
  • Elena V. Voronina (Izhevsk, Russia) 2002
  • Yuri A. Babanov (Ekaterinburg, Russia) 2001
  • Anna F. Sidorenko (Ekaterinburg, Russia) 2000
  • Santosh K. Joshi (Ratlam, India) 2000
  • Djibril Diop (Dakar, Senagal) 1998
  • Wolfgang Shattke (Kiel, Germany) 1997
  • Muhamad Islam (Bangradesh) 1996

 


Guide line for graduate course lecture(pdf file)


 

 

 

 

Recent Publications:

l   K.Nitta, Y.Omori, D.Kikuchi, T.Miyanaga, K.Takegahara, H.Sugawara, H.Sato, Local Static Distortion of Rare Earth Ions in ROs4Sb12 (R = La, Ce, Pr, Nd, Sm) by Extended X-ray Absorption Fine Structure, 77, 063601-3 (2008).

l  H.Ikemoto and T.Miyanaga, Extended X-ray Absorption Fine Structure Study of Local Structure and Atomic Correlations of Tellurium Nanoparticles, Phys. Rev. Lett, 99, 165503 (2007)@

l  T.Miyanaga, T.Azuhata, S.Matsuda, Y.Ishikawa, S.Sasaki, T.Uruga, H.Tanida, S.F.Chichibu, T.Sota, Atomic distribution in InxGa1-xN single-quanum-wells studied by extended X-ray absorption fine structure, Phys. Rev. B, 76, 035314-1-5 (2007) .

l  T.Miyanaga, T.Ogasawara, T.Okazaki, Y.Sakisaka, K.Okamoto, S.Nagamatsu, T.Fujikawa, Local magnetic structures of Ni-Mn alloys in ordered and disordered states studied by magnetic XAFS, J. Mag. Mag. Mater., 310, e601-e603 (2007).

l  T.Miyanaga, Y.Suzuki, S.Ohwada, M.Yamamoto, T.Nanke, T.Kobayashi, A.Iwasaki, Local Structure of Ag/Au Core/Shell Nano-Particles Studied by XAFS, e-J. Surf. Sci. Nanotech. 4, 138-143 (2006).

l  K.Szymanski, D.Satula, L.Dobrzynski, E.Volonina, E.P.Yelsukov, T.Miyanaga, Arrangements of magnetic moments in nanocrystalline Fe48Al52. Phys. Rev. B 72, 104409 (2005)

l  T.Miyanaga, T.Okazaki, R.Maruko, S.Nagamatsu, T.Fujikawa, Y.Sakisaka, Mn K-edge magnetic EXAFS for Ni-Mn alloys, Physica Scripta,T115, 632-634 (2005).


A more complete list of publications is availabvle here