The Physical Society of Japan: 3rd (2022) Fumiko Yonezawa Memorial Prize

JPS

The late Fumiko Yonezawa, emeritus professor of Keio University, made major contributions to physics, such as the development of the coherent potential approximation, and the theory of the metal-insulator transition in liquid selenium. Prof. Yonezawa served as the first female president of the Physical Society of Japan (JPS) and as the president of the Society for Women Scientists for a Bright Future, she also promoted female scientists.

In 2020, JPS established the "Fumiko Yonezawa Memorial Prize" to celebrate the achievements of Prof. Yonezawa and to honor and encourage the activities of the women who are members of JPS.

Prize winners are selected once a year, with a maximum of about five recipients. The prize ceremony is held during the annual meeting of JPS. The prize recipients are expected to present commemorative lectures at JPS meetings within a period of one year after receiving the prize. Winners receive items such as certificates and honorary shields, as well as additional prizes, namely: (1) paid attendance fees for JPS meetings for the next 3 years; and (2) an exemption, of up to 200,000 JPY (yen), from publication fees and open access fees for the Journal of the Physical Society of Japan, and from the article processing charges for the journal, Progress of Theoretical and Experimental Physics (valid for three years for submissions after the prize is received).

The citations of the winners of the 3rd (2022) Fumiko Yonezawa Memorial Prize are listed below.

Natsumi Iwata

Associate Professor, Institute for Advanced Co-Creation Studies, Osaka University

Theoretical study of high energy density plasma dynamics driven by intense light

Irradiating high-power lasers in the relativistic intensity level ionizes materials, thereby creating a high-energy density plasma. In such situations, the strong laser radiation at the gigabar pressure 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. Dr. Iwata also 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 Bayesian inference and obtained, for example, a scaling law in ion acceleration driven by strong laser light, thereby contributing to the development of data-analysis methods.

We have concluded that Dr. Iwata's scientific achievements deserve the Fumiko Yonezawa Memorial Prize of the Physical Society of Japan.

Keiko Takase

NTT Basic Research Laboratories, Senior Research Scientist

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. Furthermore, Dr. Takase succeeded in fabricating FETs using III-V semiconductor nanowires such as InAs and InSb, in collaboration with a materials scientist specializing in nanowire growth, using MOVPE (metalorganic vapor phase epitaxy). Due to their large spin-orbit interaction, these semiconductors are expected to have potential applications in the field of spintronics. Measurements in extreme environments, such as low temperatures and strong magnetic fields, 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 savings of FET in the future.

Dr. Takase's continuous research activities, evident in publications and various awards, as well as her outreach activities make her a role model for young female researchers. Dr Takase thus deserves to receive the Fumiko Yonezawa Memorial Prize of the Physical Society of Japan.