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The 3rd Fumiko Yonezawa Memorial Award of the Physical Society of Japan

Language : 日本語

We are happy to announce the Third (2022) Fumiko Yonezawa Memorial Award winners.

Natsumi Iwata Keiko Takase

※In the order of the Japanese syllabary/titles omitted

Full Name Natsumi Iwata
Affiliation Associate Professor, Institute for Advanced Co-Creation Studies, Osaka University
Achievement Theoretical study of high energy density plasma dynamics driven by intense light

 Irradiating high-power lasers in the relativistic intensity level ionizes a material, thereby creating a high-energy density plasma. In such situations, the strong laser radiation pressure of giga-bar level pushes the irradiated plasma surface, where electron acceleration by lasers in the relativistic regime and heating of the high-temperature plasma occur simultaneously. It is an important issue in plasma physics to explore phenomena in such extreme conditions.
 Dr. Natsumi Iwata has been theoretically studying the dynamics of high-energy density plasma driven by high-power lasers. She proposed that the plasma induces a strong electric field in the picosecond regime at the irradiated plasma surface and thus stops pushing the surface due to the laser radiation pressure, and clarified that continuous irradiation of lasers gives rise to the blowout of the heated plasma, resulting in a strong acceleration of plasma particles. Furthermore, highlighting the fact that there is a transition in plasma behavior, under continuous laser irradiation, to a statistical regime where random scatterings due to fluctuating electromagnetic fields become dominant, Dr. Iwata conducted simulations for time evolution of the electron energy under statistical scatterings and presented the corresponding plasma expansion theory. In particular, she elucidated that a coupling to fluctuating electromagnetic fields changes the electron dynamics from ballistic to diffusive and thus suppresses the scattering of electrons, leading to a confinement of the high-energy density plasma. In a more recent study, she proposed a statistical approach to the multivariate analysis of experimental data using the Bayesian inference and obtained, for example, a scaling law in the ion acceleration driven by the strong laser light, thereby contributing to the development of data-analysis methods.
 These observations lead us to conclude that Dr. Iwata's scientific achievements deserve the Fumiko Yonezawa Memorial Prize of the Physical Society of Japan.

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Full Name Keiko Takase
Affiliation NTT Basic Research Laboratories, Senior Research Scientist
Achievement Research on quantum transport and control of spin-orbit interaction in novel semiconductor materials

 Dr. Takase has been both experimentally and theoretically studying the quantum properties of quantum effect devices in semiconductor materials such as graphene and III-V semiconductor nanowires. In graphene research, she succeeded in fabricating wafer-scale epitaxial graphene on a silicon carbide (SiC) substrate. Transport spectroscopy of the fabricated graphene field effect transistor (FET) on SiC and the theoretical model elucidated the quantum properties of epitaxial graphene. Then, Dr. Takase succeeded in fabricating FETs using III-V semiconductor nanowires such as InAs and InSb in collaboration with a materials scientist of nanowire growth using the MOVPE (Metalorganic vapor phase epitaxy). Because of a large spin-orbit interaction these semiconductors are expected to have potential applications in the field of spintronics. Measurements in extreme environments such as low temperature and strong magnetic field and theoretical calculations revealed that the FET fabricated by Takase, et al. can efficiently control a large spin-orbit interaction at a low gate voltage. It is expected to lead to energy saving of FET in the future.
 Dr. Takase's continuous research activities proven in publications and various awards as well as her outreach activities will make her recognized as a role model for young female researchers. Dr Takase thus deserves to receive the Fumiko Yonezawa Memorial Prize of the Physical Society of Japan.

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