The Physical Society of Japan: 2nd (2021)
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 the of 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 women scientists.

JPS has 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.

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

The citations of the winners of the 2nd (2021) Fumiko Yonezawa Memorial Prize are listed below.

Yu Nakahama

Associate Professor, Kobayashi-Maskawa Institute for the Origin of Particles and the Universe (KMI), Nagoya University

Study on new phenomena beyond the standard model of particle physics

The unification of forces and an understanding of the vacuum are targets of elementary particle physics. Super-symmetric theory (SUSY) has been a strong candidate of the unified theory due to its theoretical simpleness. On the other hand, dark matter has been established from cosmological observations and is commonly thought as yet-unknown elementary particles which SUSY can describe. Discovery of the Higgs particle is a clue to understand the vacuum, and precise investigation of the Higgs field including Higgs self-coupling is thought to be a direction for the next efforts in particle physics.

Verification of the SUSY or beyond the standard particle theory is widely pursued by looking for the production of new particles and/or discrepancies from the standard theory in precise measurements and rare phenomena. Dr. Nakahama introduced a new method to measure CP asymmetries in neutral current decay of B mesons at the Belle experiment and concluded no discrepancy from the standard theory. Then, in the ATLAS (A Toroidal LHC ApparatuS) experiment, she led the search for SUSY gluino and squark inclusively and rejected many SUSY and dark matter models. Her work has had a strong impact in both the field of elementary particle physics and cosmology. She has pioneered the use of deep learning tools in the investigation of the Higgs field. Improvement of the ATLAS trigger performance is indispensable in upgrading the luminosity of the LHC (Large Hardon Collider). Her work as a person in charge of the ATLAS trigger selection project was instrumental in the Run 2 operation of the LHC and was highly praised.

Dr. Nakahama worked at the Belle experiment, at the precision frontier of high energy physics. Then, she continued her research at the ATLAS experiment, at the high energy frontier, and had various achievements. Consequently, she has been promoted to important posts in the group and is a good role model for researchers in particle experiments using an accelerator. She is serving as a committee member for future planning in the high energy physics community. Her contributions continue to propel the field forward. As described above, Dr. Nakahama deserves to receive the Fumiko Yonezawa Memorial Prize as she is a young researcher who is a leader in experimental particle physics.

Emi Minamitani

Associate Professor, Institute for Molecular Science

Computational study of nanoscale magnetism and phonon

Dr. Emi Minamitani is a theorist who has been studying magnetism and phonon physics in nanoscale systems by employing cutting-edge computational science approaches. In particular, she uncovered novel quantum phenomena emerging on solid surfaces through close collaborations with experimentalists.

One of her important achievements is the study of the Kondo effect for molecules adsorbed on surfaces. Recently, it has become possible to observe the Kondo effect of atoms/molecules on solid surfaces by STM (Scanning Tunneling Microscope) experiments. Focusing on the flexibility of the shape of molecules as well as their orbital degrees of freedom, she developed a theory incorporating the Kondo effect and the interference effect between different channels in STM currents. Applying this theory, she found the SU(4) Kondo effect with spin/orbital degrees of freedom in a single iron phthalocyanine molecule and further proposed the possibility for reversible control of quantum phase transitions due to competition between the Kondo effect and the magnetic anisotropy. These phenomena were confirmed experimentally.

As another important achievement, she developed a theory of "STM-inelastic electron tunneling spectroscopy (STM-IETS)." In this method, one can detect phonon excitations that are induced by the electron tunneling from an STM tip to a surface. She clarified that the characteristic profile of the tunneling spectrum is determined by the strong momentum/energy dependence of the electron-phonon interaction, thereby explaining the peculiar experimental spectrum observed for the Cu(110) surface. She also succeeded in applying this theory to a graphene/SiC interface. These systematic studies have paved the way to explore phonon excitations on surfaces with the STM-IETS.

Dr. Minamitani's scientific achievements deserve recognition through the Fumiko Yonezawa Memorial Prize of the Physical Society of Japan.

Hiroko Yokota

Associate Professor, Faculty of Science, Chiba University

Nano-heterostructures in ferroics and new functionalities appeared at their boundaries

Dr. Yokota's work has focused on the phase and domain boundaries in ferroic materials. First, for the piezoelectric solid solution system , she has revealed the coexistence of multiple crystal structures by high-resolution neutron diffraction experiments. Moreover, based on the precise analysis of the structurale data with the PDF method, she experimentally confirmed the rotation of polarization, which had been theoretically proposed to cause a giant effect. Second, for inherently non-polar ferroelastic compounds, she used an optical 2nd harmonic generation microscope and successfully observed that the domain boundaries show polarization. These results indicate that the physical properties at domain or heterostructure boundaries are different from bulk properties, which contributes to the establishment of a new field in solid state physics.

The Scope of Dr. Yokota's research is evident through her many publications, invited talks, and various awards. She is anticipated to be a role model for young women who are researchers and her work deserves to be recognized through the Fumiko Yonezawa Memorial Prize.

Hiroko Watanabe

Assistant Professor, Research Center for Neutrino Science, Tohoku University

Research on cosmic ray variations during grand solar measuring the Earth's neutrino flux and constraining its composition

Neutrino detections in Kamioka Mine, which was originally designed to search for proton decay, have achieved significant progress in size and precision since Kamiokande (from 1983), Super-Kamiokande (from 1996), and KamLAND (from 2002). Hyper-Kamiokande is expected to begin in 2027. The renowned results at Kamioka Mine that brought two Nobel prizes to Japan are assoicated to studies in super-nova neutrinos, solar neutrinos, and atmospheric neutrino oscillation. Amongst those results, an especially prominent outcome is from geo-neutrino detections conducted at KamLAND, which is a major achievement of Prof. Hiroko Watanabe. Geo neutrinos are produced by radioactive decays of thorium and uranium in the crust and the mantle of Earth, and are one of the important heat sources of Earth. The heat balance of Earth had been one of the long-standing puzzles in earth science for over two centuries. Prof. Watanabe and her collaborators determined the geo-neutrino flux, and were able to put stringent constraints on heat models of Earth through detailed comparisons between reactor neutrinos and geo-neutrinos. While the first detection of the geo-neutrino by KamLAND was made in 2005, her result established a new interdisciplinary field,- "neutrino earth science," which integrated neutrino physics and earth science. Prof. Watanabe is the corresponding author of the epoch-mkaing paper titled "Reactor on-off antineutrino measurement with KamLAND" and has presented related works in many invited talks and plenary talks internationally. She is and will continue to be the leading scientist of "neutrino earth science" and she is presently promoting the separation of crust-origin neutrinos and mantle-origin neutrinos with a directionally sensitive neutrino-detection technology. Prof. Watanabe's work deserves to be recognized through the Fumiko Yonezawa Memorial Prize.