Akihiko SUMIYAMA
Professor, Graduate School of Material Science, University of Hyogo- Topics of Research：
- Study of multiple superconducting phases in heavy-fermion materials using tunneling phenomena
■ Laboratory Website
■ Description of Research
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RESEARCH
I have been studying on superconductivity at low temperatures (<1K) using a dilution refrigerator and a SQUID (Superconducting QUantum Interference Device). One of the subjects I am now concentrating on is the Josephson effect that enables zero-resistance current to flow through a normal metal inserted between two superconductors. This occurs by the quantum mechanical property of superconductivity and has given useful information on unconventional superconductivity in heavy-fermion materials.
In this project, I am going to investigate multiple superconducting phases of heavy-fermion U compounds using tunneling phenomena, such as the Josephson effect described above and the tunneling spectroscopy between a superconductor and a normal metal. The figure shows the magnetic-field dependence of Josephson critical current of UPt3, which shows multiple superconducting phases. As compared with the previous result in (a), the recent result in (b) shows a Fraunhofer diffraction pattern in the same manner as the diffraction of light, indicating the improvement of the junction quality.
EDUCATION
- 1981
- Bachelor of Science (Physics), The University of Tokyo
- 1983
- Master of Science (Physics), The University of Tokyo
- 1986
- Ph.D. (Science), The University of Tokyo
PROFESSIONAL EXPERIENCE
- 1986-1989
- Research Center, Mitsubishi Chemical Industries Limited
- 1990-1993
- Lecturer, Faculty of Science, Himeji Institute of Technology
- 1993-2008
- Assistant Professor, Faculty of Science, Himeji Institute of Technology
- (2004
- Himeji Institute of Technology was integrated into University of Hyogo)
- 2008-Present
- Professor, Graduate School of Material Science, University of Hyogo
SELECTION OF PUBLICATIONS
"Magnetic-Field Modulation of the Josephson Effect between URu2Si2 and Al",
A. Sumiyama, K. Hikawa, J. Gouchi, G. Motoyama, A. Yamaguchi, T. Honma, E. Yamamoto, Y. Haga, and Y. Onuki,
J. Phys. Soc. Jpn. 82, 025005(1)-(2) (2013).
"Measurement of the Josephson Effect of Heavy-Fermion Superconductor UPt3 as a Test of the Odd-Parity Order Parameter",
J. Gouchi, A. Sumiyama, G. Motoyama, A. Yamaguchi, N. Kimura, E. Yamamoto, Y. Haga, and Y. Onuki,
J. Phys. Soc. Jpn. 81, 113701(1)-(4) (2012).
"Josephson Effect between Noncentrosymmetric LaPt3Si and a Conventional Superconductor",
Y. Aoki, A. Sumiyama, M. Shiotsuki, G. Motoyama, A. Yamaguchi, Y. Oda, T. Yasuda, R. Settai, and Y. Onuki,
J. Phys. Soc. Jpn. 79, 124707(1)-(6) (2010).
"Magnetic-field modulation of the Josephson effect in heavy-fermion superconductor CeIrIn5",
A. Sumiyama, Y. Tsuji, Y. Oda, H. Shishido, R. Settai, and Y. Onuki,
J. Mag. Mag. Mater. 310, 599-601 (2007).
"Josephson Effect between CePt3Si and an s-Wave Superconductor",
A. Sumiyama, K. Nakatsuji, Y. Tsuji, Y. Oda, T. Yasuda, R. Settai, and Y. Onuki,
J. Phys. Soc. Jpn. 74, 3041-3045 (2005).
"Magnetic Field Modulation of the Josephson Effect between UPt3 and a Conventional Superconductor",
A. Sumiyama, R. Hata, Y. Oda, N. Kimura, E. Yamamoto, Y. Haga, and Y. Onuki,
Phys. Rev. B 72, 174507(1)-(5) (2005).
"Josephson Effect in Weak Links between URu2Si2 and Nb",
R. Tachibana, A. Sumiyama, Y. Oda, E. Yamamoto, Y. Haga, T. Honma, and Y. Onuki,
J. Phys. Soc. Jpn. 72, 364-368 (2003).
