The motivation

The project was initiated by the center's director and principal investigator, Arne Brataas. There were several articles in high profile journals on two-dimensional magnets that had caught his interest. These discoveries opened up new and exciting doors in exploring magnetism in the flatland. Advancement in the field was happening fast. Arne realized that we could further exploit our knowledge of current-induced magnetization dynamics and spin-pumping to push the frontier of this rapidly progressing field. The questions were how QuSpin could contribute to research, which material to focus on, which direction to explore first, and who should be involved. These questions were also an excellent opportunity to enhance the collaborations within the center.

‘There is usually a more clear goal at the beginning. However, we knew that the systems were important to investigate.’ – Arne Brataas

The walk

Typically, in the hard sciences, professors assign a topic to study to a Ph.D. student or post-doc. In this case, instead of just having one Ph.D. candidate exploring the subject, Vetle Kjær Risinggård, and Øyvind Johansen, as well as primary investigator, Jacob Linder, joined to collaborate. The Ph.D. students had an initial path to follow but as far as to what material to work with, and other conclusions   to draw from the study, it was up to them. They had many opportunities and challenges. Before the Ph.D students joined, in the early discussions, the investigating team included Sol Jacobsen, but due to the pressing nature and the timing of the work, they continued on themselves when she left for maternity leave.

‘Normally, a research is to investigate or compute a particular quality and look for any interesting outcome. But this time we had the idea of finding an exciting material to study. We could look for any properties we could find that were of interest.’ – Jacob Linder

Vetle and Øyvind worked on analysis and modeling. Their starting point was an existing framework developed by Arne Brataas and a former post-doc, Kjetil Hals, whch iis now a professor at the University of Agder. Øyvind suggested considering the material Fe3GeTe2 because of its unique symmetrical properties. They believed it had the desired features required to change the magnetic state with currents. The material had to have the right crystal structure. The symmetry had to be low enough to be able to manipulate the direction of the 2D magnetic field in the material.

‘Everything that is not forbidden, is compulsory.‘
– Vetle Kjær Risingggård

They also learned, from recent research, that experiments with the Fe3GeTe2 material could take place in a warmer environment than earlier attempts. They concluded they could work at the temperature of -150 C; one hundred degrees warmer than earlier work by other researchers.

The informal meetings places

Informal meetings enable the exchange and development of new ideas. In a group of people with diverse backgrounds, our combined lunch and seminar room allows for spontaneous encounters and a more open line of communication. At QuSpin we are certainly seeing more collaboration and interaction than before, and its benefits. Scientific and interpersonal relationships benefit from informal meeting places and, at QuSpin, it played an essential role in the second part of their project.

Vetle and Øyvind were discussing their work with principal investigator, Asle Sudbø, over a cup of coffee in the lunchroom on the 5th floor. They had discovered that the direction of the 2D magnets could turn vertically or horizontally in the material while magnetic. But, the material was non-magnetic exactly between these positions. Asle pointed out that by using a precise current, one might see an interesting type of phase transition in the system between the vertical and horizontal magnetic states. With this, he widened the original scope of the study. The nature of this phase transition is usually very difficult to explore, except at ridiculously low temperatures. This material offered new revelations at temperatures that are routinely achieved in laboratories.

After explaining their observations of the current control, Asle commented, ‘You have more here than you think!’

Øyvind and Vetle went back to their research and Asle joined the team. What Asle pointed out helped to widen the study and made the paper interesting to a broader scientific audience. The target publication moved from a Physical Review B (PRB), up to a Physical Review Letter (PRL).

After the article was published, we had an opportunity to discuss the work during an informal exchange at our internal collaboration workshop in Oppdal. Our German experimentalist colleague, Co-principal investigator, Mathias Kläui, had seen the article. Coincidentally, his team had some interest in the same material. The road is nowlaid open to test the conclusions in the experimental lab, if possible. The collaboration between our theoretical and experimental research is an opportunity and a possible next step to prove the findings in the article.

Strategic supervision, intuition and luck When writing scientific papers, people have different roles. Varied input comes from putting more senior researchers together with the younger researchers. Often, Phd candidates carry out the technical work. In the regular project meetings, the main role of principal investigators is to mentor and supervise. They evaluate findings to ensure consistency and look for new possibilities. They help guide through the direction and steps to be taken next. With their years of experience, they have developed a sense of intuition and insight of what to look for and those skills can help make sense of the findings. There can be a lot of random events that follow, but, by coordinating efforts and persevering, understanding the results is made possible.

It is essential to have the skills and experience to explore all the opportunities as they emerge.
– Arne Brataas

This creativity and sensibility is something the Ph.D.s will develop over time. The supervisors have experience publishing papers in the scientific community. They understand what the referees look for in a successful paper. They are aware of what the potential critical points are in the study and how to solve or approach them. Because of their central role, supervisors are co-authors on papers in the hard sciences. It’s a kind of quality assurance. ‘Ultimately, it is the quality of the science that matters, not the number of papers.’ adds Arne.

‘There is no such thing as sheer luck, but at the same time, it is about luck, depending on the interest of the referee and other articles up for evaluation.’ – Jacob Linder

Øyvind and Vetle found an open culture at QuSpin. Everyone is involved and the process is dynamic. They were able to generate and present their own ideas and their points were listened to. The principal investigators were approachable and collaborative. It is a generous learning environment. Some of the conclusions being drawn from the work ran contrary to conclusions published by Arne himself. He shrugs and smiles as he mentions this himself in the meeting. ‘It’s weird, but it happens. It’s still weird.’

‘A lot of time was spent thinking about how to sell the results. Why should people care about this?’ – Arne Brataas

Experienced Ph.D. candidates

In such an open-ended project it was valuable to have two very experienced Ph.D. candidates in the project. Arne and Jacob were confident giving a more open ended brief to begin with.

‘It was good we had two experienced Ph.D. students. Less experienced students with an unclear goal could have been more frustrated.And it would have taken longer.’
– Arne Brataas and Jacob Linder

They may have been in a hurry to study the 2D magnetic properties, but they took their time to understand the results. ‘For example', Øyvind adds, ‘most of the results on the paper were discovered in the last quarter of the project.’

Insights for the future

Through this type of research, we reveal information about a wide range of systems with similar physical phenomena that exhibit similar behavior. Our prime interest is knowledge. This is the key. Usefulness is also of interest, but secondary, and in the long run, most likely, for others to explore. It could take 10-30 years before it is realized.

Looking for new insights in physical phenomena can  lead to new and interesting discoveries. That, in turn, can open up new horizons. We certainly feel that our findings, through the collaboration in this open-ended assignment, has the potential of being a valuable contribution to international research and possible future results. It was an exciting walk together with a rewarding destination!