Osamu ISHIKAWA
Professor, Graduate School of Sciences, Osaka City University- Field of Specialty：
- Ultra low temperature physics
- Topics of Research：
- (B01) Novel Edge Phenomena in Spin-Triplet Superfluids
- Specific Topics：
- Study of superfluid 3He and quantum phase transition phenomena
RESEARCH
I have been studying superfluidty of 3He, 4He, and 3He-4He dilute mixture. In pure liquids of helium free from any impurities at low temperatures, it is possible to observe not only intrinsic properties in the ground state but also exotic phenomena due to low energy excited states. Nuclear magnetic resonance (NMR) method, resonating sound method, and resonating oscillations method are powerful experimental tools to analyze basic properties of superfluids. In 19XX, I tried to find superfluidity of 3He (Fermi particles) dissolved in the Bose condensate (superfluid 4He). Unfortunately, we could not catch any signs of superfluidity at that time. But our reaching temperature in this experiment 97 μk has been the world record even now. This issue still attracts many scientists in low temperature physics. Recently I have studied exotic properties of superfluid 3He in spatially restricted geometry and those of rotating superfluid 3He. When the dimension of the restricted space is comparable to the coherence length, usual superfluid phase is suppressed. However, at the same time, another new type condensed states would be expected. A quantum vortex of rotating superfluid 3He is not simple "phase vortex" as that in superfluid 4He but is accompanied by the texture variation around the vortex. Such a stable state of the quantum vortex would be characterized by some topological numbers.
In this project, I intend to study novel boundary phenomena of superfluid 3He in restricted geometries. The pairing symmetry of 3He in aerogel is also an important and interesting issue because the random potentials of aerogel may be a source of a new pairing state so called odd-frequency symmetry state. Such a new pairing state was first predicted in a proximity structure of spin-triplet superconductor Sr2RuO4. The similar symmetry change of pair is also expected in 3He in inhomogeneous circumstance. These studies will be done in collaboration with A01, C01 and D01 groups. In rotating superfluid experiments, I try to solve a very important open problem so called intrinsic angular momentum of 3He-A phase . The intrinsic angular momentum of the Cooper pair has been theoretical predicted since the discovery of superfluid 3He. Experimentally, however, we have never confirmed evidence of the intrinsic angular momentum. In collaboration with D01, I also try to observe a half quantum vortex expected in 3He-A phase under restricted geometry. The half quantum vortex is also a very interesting topological matter though it has not been discovered yet.
EDUCATION
- 1980
- Bachelor of Science (Physics), Kyoto University
- 1988
- Ph.D. in Science, Kyoto University
PROFESSIONAL EXPERIENCE
- 1986-2009
- Assistant, lecturer , Assistant Professor, Faculty of Science, Osaka City University
- 1996-1998
- Visiting Researcher, University of California, Berkeley
- 2003-2004
- Visiting assistant professor, Institute of Solid State Physics
- 2009-Present
- Professor, Graduate School of Science, Osaka City University
SELECTION OF PUBLICATIONS
"Enhancement of magnetization in liquid 3He at aerogel interface",
A. Fukui, K. Kondo, C. Kato, K. Obara, H. Yano, O. Ishikawa and T. Hata,
Journal of Low Temperature Physics 172, 245-250 (2013).
"Acoustic Resonance of Superfluid 3He in Parallel Plates",
K. Obara, C. Kato, S. Sasamoto, H. Yano, O. Ishikawa, T. Hata, S. Higashitani, K. Nagai,
Journal of Low TemperuturePhysics 162, 190-195 (Nov. 2010).
"Frictional motion of normal-fluid component of superfluid 3He in aerogel",
K. Obara, C. Kato, T. Matsukura, Y. Nago, R. Kado, H. Yano, O. Ishikawa, T. Hata, S. Higashitani, K. Nagai,
Physical Review B 82, 054521-1-7 (Aug. 2010).
"In globally isotropic aerogel, A-B phase separation of superfluid 3He in radial direction",
Journal of Physics, Conference Series 150, 032036-1-4 (2009) .
"Spin Wave and Vortex Excitations of Superfluid 3He-A in Parallel-Plate Geometry",
M. Yamashita, K. Izumina, A. Matsubara, Y. Sasaki, O. Ishikawa, T. Takagi, M. Kubota, and T. Mizusaki,
Phys. Rev. Lett. 101, 025302 (2008).
"A-B phase conversion and coexistence of superfluid 3He in aerogel",
R. Kado, H. Nakagawa, K. Obara, H. Yano, O. Ishikawa, and T. Hata,
J. Low Temp. Phys. 150, 472-475 (2008).
"The Orientation Effects of Superfluid 3He in Anisotropic Aerogel",
T. Kunimatsu, T. Sato, K. Izumina, A. Matsubara, Y. Sasaki, M. Kubota,
O. Ishikawa,
T. Mizusaki, and Yu.M. Bumkov,
JETP LETT. 86 216-220 (2007).
"Equal-spin- paring superfluid phase 3He in aerogel acting as an impurity",
H. Nakagawa, R. Kado, Handa, K. Obara, H. Yano, O. Ishikawa, T. Hata,
H. Yokogawa, and M. Yokoyama,
Phys. Rev. B 76, 172504 (2007).
"Pinning of Texture and Vortices of the Rotating B-like phase of Superfluid 3He Confined in a 98% Aerogel",
M.Yamashita, A.Matsubara, R.Ishiguro, Y.Sasaki, Y.Kataoka, M.Kubota,
O.Ishikawa, Yu.M.Bunkov, T.Ohmi, T.Takagi and T.Mizusaki,
Phys. Rev. Lett. 94, 075301-1-075301-4 (2005).
"Phase-Transition Phenomena of 0.8 mm Superfluid 3He Slab",
K.Kawasaki, T.Yoshida, M.Tarui, H.Nakagawa, H.Yano, O.Ishikawa, and T.Hata,
Phys.Rev.Lett. 93, 105301-1 -105301-4 (2004).
"Pressure dependence of the A-B phase transition temperature in superfluid 3He in
1.1 mm slab geometry",
S.Miyawaki, K.Kawasaki, H.Inaba, A.Matsubara, O.Ishikawa, T.Hata, and T.Kodama,
Phys. Rev. B 62, 5855-5864(2000).
