[No. 200] Atsufumi Hirohata

It was at the welcome party for the Department of Physics, after we had been assigned to our departments, that the Department Head said, "Physics is the only discipline that is meaningful as a field of study even without the character for 'study' (学, *gaku*) in its name." It was an opportunity to reaffirm the appeal of physics as a discipline that literally clarifies the "principles of things."

Looking back, ever since I was in elementary school and encountered cutting-edge rockets and moon rocks at a space exhibition held at the Museum of Maritime Science, I had been interested in elucidating natural phenomena, so I was relieved to have made the optimal choice. However, the path to get there (and even after) was by no means smooth.

In high school, I was thinking of going on to the Faculty of Economics with the aim of working at the United Nations, but a senior in my club convinced me of the appeal of physics, so I chose the science track. However, my physics grades on mock exams and the like were poor (my lowest deviation score was 35), and it was only after studying for an extra year as a *rōnin* that I was finally able to enter the Faculty of Science and Technology at Keio University. After that, I continued to struggle, especially with mechanics, and I had to repeat a year before finally being assigned to a laboratory.

I chose Professor Miyajima's laboratory (now the Nozaki Laboratory). It was located in the back of the first floor of Building 22, and the lights were always on, indicating active research. (Of course, other labs were active too, but I chose this one because my grades in electromagnetism were good.) It was very popular, and I won my spot through a game of rock-paper-scissors. I had just graduated from the Athletic Association's rifle shooting club (not the carnival game, just to be clear), which I had dedicated myself to for four years of university, so I was able to concentrate 100% on my life in the laboratory.

The paper I was in charge of for our journal club, in particular, remains one of the cornerstones of my research today. In the lab, we often had to stay overnight to conduct experiments due to equipment reservation schedules, and I bonded with my lab mates over food and drinks. We would deepen our friendships almost every week in Hiyoshi, saying things like, "First a drink just looking at the kimchi, then another after the first bite." Renting a car and going on trips together when attending academic conferences are also fond memories.

In the Miyajima Lab, I observed the magnetic domain structure of Ni-Fe alloys using a magnetic force microscope, which had only recently been introduced at the time. Fortunately, I was able to summarize my work in two papers and present it twice at international conferences. When I advanced to the master's program, my interest in research on devices using electron spin transport grew, and with the help of a researcher from France and Professor Eto, I decided to study abroad. I requested information from universities in the UK, US, and France, and applied to the British universities that responded. Among them, I received a positive response from Professor Bland of the University of Cambridge. As he was scheduled to give a lecture at Toshiba, I was able to meet him at the Shinagawa Prince Hotel. From there, things moved quickly, and my admission to the doctoral program abroad was decided.

The Bland Lab had nearly 30 students and postdocs (an unusually large scale for the UK), and it was an environment where colleagues could freely advance their research. I pursued a two-pronged research approach: spin-polarized electron excitation using circularly polarized light and thin-film/device evaluation using a magnetic force microscope. The professor would jokingly say, "International students produce great research results because they can't go home as often (as British students)." It is also a great treasure that I made lifelong friends, including students from the same college (which handles small-group education and student dormitories, in contrast to the university, which is mainly responsible for education and research), with whom I shared lodgings.

I spent about four and a half years in Cambridge, including my time as a postdoc, but my desire to acquire new skills, including microfabrication, grew, and I began looking for new positions, mainly in Germany and the US. After applying to over 30 positions, Professor Moodera at the Massachusetts Institute of Technology accepted me, and I was able to work on the development of phase-change memory and research on magnetic tunnel junctions.

After that, I worked as a CREST researcher under Professor Inomata at Tohoku University, researching Heusler alloy thin films, and then devoted myself to developing nanoscale devices at the Otani Lab at RIKEN. In 2007, there was an open position at the University of York in the UK, and I was able to establish my own laboratory. Using the techniques I have learned at various institutions, I am now developing new magnetic materials and spintronic devices, as well as establishing non-destructive imaging methods.

Through these experiences in Japan, the US, and Europe, I was also able to learn about the different attitudes toward research among researchers from various countries around the world. Specifically, I have noticed broad differences, such as the UK aiming for "smart" research, the US being application-oriented, and Japan excelling at systematic research. I try to conduct my research in a way that leverages the strengths of each international student and postdoc from various countries, including their different approaches to research. I believe a PhD is like a driver's license, and I want to train researchers who can navigate any rough road. Although the success rate for research funding in the UK is much lower than in Japan, I aim to become one of the hubs for spintronics research, including through broad collaborations with Japan and other countries.

In closing, I would like to express my sincere gratitude for the opportunity to contribute to the Keio University alumni relay column. Although my writing may be clumsy, I hope I have conveyed some of the appeal of physics (especially magnetism and spintronics), and that it might inspire even one more person to spread their wings and venture out into the world.