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2012 Awards

Award for Academic Papers on Physics

The selection committee has chosen the following five papers for the award in 2012 out of 17 nominations made by the editors of the two journals and representatives of the 19 divisions of the society.

Title Causal Relationship between Zonal Flow and Turbulence in a Toroidal Plasma
Journal J. Phys. Soc. Jpn., Vol.76, 033501, (2007)
Authors Akihide Fujisawa, Akihiro Shimizu, Haruhisa Nakano, Shinsuke Ohshima, Kimitaka Itoh, Yoshihiko Nagashima, Sanae-I. Itoh, Harukazu Iguchi, Yasuo Yoshimura, Takashi Minami, Keiichi Nagaoka, Chihiro Takahashi, Mamoru Kojima, Shin Nishimura, Mitsutaka Isobe, Chihiro Suzuki, Tsuyoshi Akiyama, Takeshi Ido, Keisuke Matsuoka, Shoichi Okamura, Patrick H. Diamond:

In this paper, the authors reported their experimental identification of the role of microscopic turbulence in generating a meso-scale electric field and flow (zonal flow) in nonequilibrium toroidal plasmas. Theories have predicted that microscopic turbulence in confined plasmas induce the transport and zonal flows, which are constant on a magnetic surface (but change signs in radius). In this paper, the first experimental identification of the process was reported, stating that zonal flows are driven by microscopic turbulence and suppress the turbulent transport. This paper has given a firm experimental foundation for the understanding of the process by which a large-scale structure in the vector field is generated by an inhomogeneous global scalar field. This article has given a scientific basis for the realization of controlled fusion and for the understanding of turbulent structures (including dynamos) in nature. This is a distinguished paper that has opened a new arena in experimental plasma physics.

Title Ferroelectricity Induced by Proper-Screw Type Magnetic Order
Journal J. Phys. Soc. Jpn., Vol. 76, 073702 (2007)
Authors Taka-hisa Arima
Marks Generally it is believed that electricity and magnetism are independent to each other. However, in multiferroic materials, they are closely related to each other and sometimes ferroelectricity is induced accompanied with a magnetic order. There will be several mechanisms for the origin of multiferroics, and a theory by Katsura et al has been considered to explain ferroelectricity due to cycloid-type magnetic ordering. However, it turns out that there are many other materials which are not explained by this theory. For example, the magnetic-field-induced ferroelectricity in CuFeO2, which is realized in a proper-screw type ordering, cannot be explained. The present paper succeeded to solve this problem clearly. In this paper, the author took account of the p-d mixing mechanism with spin-orbit interaction and showed that ferroelectricity appears even in the proper-screw type ordering in crystals with low symmetry. Using this result, the author succeeded to explain CuFeO2. Furthermore, the mechanism proposed in this paper is quite general and it can be applied to many other materials. This paper contributes greatly to the succeeding material researches and to the understanding of the phenomena coupled with electricity and magnetism.

Title A Periodic Structure in a Mixture of D2O/3-Methylpyridine/NaBPh4induced by Solvation Effect
Journal J. Phys. Soc. Jpn., Vol. 76, 113602 (2007)
Authors Koichiro Sadakane, Hideki Seto, Hitoshi Endo, Mitsuhiro Shibayama

The authors found that when salt is added to a phase separating solution (water/3-methylpyridine), the transparent solution starts to have a color which changes from blue to green, yellow and red as the temperature is raised. They hypothesized that this is due to the formation of a large periodical structure in the solution. In this paper, they proved the existence of such a structure by small angle neutron scattering. Onuki et al theoretically predicted that when ions are added to a phase separating solution, the scattering intensity will have a peak, but there was no experimental proof. The authors hypothesized that the coloring phenomena they found is due to this effect and they confirmed their conjecture by neutron scattering. Their finding that ions create a periodical structure of wavelength 10-100 nm in solution was a surprise, and gave an impact in soft matter and statistical physics. This paper is the first of their series of works.

Title Rattling-Induced Superconductivity in the β -Pyrochlore Oxides AOs2O6
Journal J. Phys. Soc. Jpn., Vol. 78, 064702 (2009)
Authors Yohei Nagao, Jun-ichi Yamaura, Hiroki Ogusu, Yoshihiko Okamoto, Zenji Hiroi

The authors' group discovered the β-pyrochlore oxide superconductors AOs2O6 (A= Cs, Rb and K). In this paper, the authors provided systematic studies of the physical properties in the superconducting and normal states by using high quality single crystals they had grown themselves. In the series of papers that appeared before the publication of the present one (which were mainly published in J. Phys. Soc. Jpn) the authors' group had reported that these materials have cage structure and the anharmonic oscillation of alkai ions, which is called rattling motion, strongly influence many physical properties. These intriguing materials are, in particular, quite unique in that they undergo the superconducting transition. In this paper, using detailed analysis of the specific heat in high quality single crystals, the authors showed a strong coupling superconductivity in these systems, in which pairing interaction is very strong. In addition they suggested the possibility that this strong interaction may arise from the rattling motion. This suggestion made by the authors is very important for the researchers in this field. The discovery of new materials and measurements by using high quality single crystals is requisite for the progress of material science; therefore, the authors' achievement in this paper has made a high impact in the condensed matter community.

Title Theoretical Foundation of the Nuclear Force in QCD and its applications to Central and Tensor Forces in Quenched Lattice QCD Simulations
Journal Prog. Theor. Phys. 123 (2010), 89-128
Authors Sinya Aoki, Tetsuo Hatsuda, Noriyoshi Ishii

The authors (HAL collaboration) developed a novel method to extract a nuclear force from lattice QCD (quantum chromodynamics) calculations; they successfully converted the inner part of nucleon-nucleon Bethe-Salpeter amplitude to a non-local nuclear potential, which is further reduced to a sum of local potentials by derivative expansion. The present paper gives a detailed foundation of the novel method for extracting local potentials for composite particles from lattice QCD. They clarify the advantages of the method; in particular, they show that any singular behavior in the quark-mass dependence of the potential will not appear, which is in contrast to the conventional method utilizing scattering length.In short, this paper is a seminal paper which developed a novel and effective method to extract nuclear forces from quantum chromodynamics as a field theory, and thus deserves the JPS Award for Academic Papers on Physics.