He unravels the order of things

Peter Oppeneer
Professor of Materials Theory Peter Oppeneer constructs mathematical theories with the help of quantum physics, such as in the new EU-project FEMTOTERABYTE.
Photo: Mats Kamsten

How do you go about explaining or predicting the unusual properties of various materials? Physicist Peter Oppeneer uses equations for new revelations about the lowest common denominator in all materials: the electron. “Everything from computers and batteries to the cells in our bodies are made up of more or less the same atoms. From them we can build materials with new properties, but also improve health care diagnoses.”

Basic research is where he finds his passion, the professor in materials theory at the Department of Physics and Astronomy. The common thread in his research is the construction of mathematical theories with the help of quantum physics, the theory of particles smaller than atoms.

“I always start by setting up a new mathematical theory in the form of equations for an unsolved problem. If my colleagues and I are to develop a computer program, for example, the goal is to program and carefully calculate the quantitative results that the theory provides. The results we get can either be directly compared with the experiment or predict measurable results for new experiments,” says Peter Oppeneer.

“As early as during my PhD studies, I found that this is the way I prefer to do research.”

A major key to developing new material is determining how magnetic states are formed based on the material’s atoms. The electrons of the atoms are magnetic in nature. However, only when the electrons that move around the atoms are influenced by the charges of other electrons magnetism arises. This is an interaction between the particles, which are also affected by a magnetic moment of the electron called spin.

“All electrons have a spin-moment. That's why magnetism always comes into the picture in some way, and also indirectly controls so much within our bodies.”

The fact that our millions of cells are controlled by weak electric and magnetic impulses once led Peter Oppeneer to become involved in a malaria project. About ten years ago, he was doing research on magneto-optics, a method for discerning magnetism using light. One day he was approached by a group of experimental physicists in the United Kingdom and their research partners within tropical biology and medicine in the Netherlands. Could magneto-optics be used to detect malaria disease in humans?

“I knew nothing about malaria but together with my team, I started to develop a quantum theory. And through large-scale calculations we could predict how detection could be achieved,” says Peter Oppeneer.

“You can detect malaria purely optically by measuring the light absorption in a finger. What happens is that if you are infected by malaria parasites in the blood, then you also have malaria pigments. These pigments have a magnetic moment that differs from that of hemoglobin, the protein found in red blood cells in humans and many animals. It allows you to detect malaria disease with magneto-optics.”

Researchers in the United Kingdom patented the discovery, which later resulted in a diagnostic instrument for malaria. However, Peter Oppeneer was and is not interested in investing in expensive patent or product development: he wants to do basic physics.

“My goal is not to make money. I guess it’s typical of me that once I've worked on a theme and have a firm grasp of it, I begin to look for something new to catch my interest. That’s the way I’ve conducted research within a wide range of areas.”

Several of his research areas are now combined in the EU project FEMTOTERABYTE, with himself as head researcher of the theory. Besides the colleagues and materials physicists Vassilios Kapaklis and Björgvin Hjörvarsson, the project involves nanoscientists at the University of Gothenburg and physicists from the Netherlands and the United Kingdom, among others. The goal of the project is to change the direction of magnetism in a hard drive's nanometer-sized bits of information within the time range of only femtoseconds – where a femtosecond is a staggering one thousandth of a trillionth of a second.

“To change the direction of the electrons' spin in the computer's bits means changing the sequence of ones and zeros in the information bits. When the pace of this change increases, information can be written to and read from the magnetic hard disk faster,” explains Peter Oppeneer.

“If we manage to achieve this, it may lead to a revolution within magnetic data storage, which would become much faster and able to handle and store even larger amounts of data in the future.”

In fact, Peter Oppeneer and his group have already taken a big step on the way as the first researchers in the world to have demonstrated that exposure to light can induce magnetization within less than 100 femtoseconds.

“Last year, we were able to calculate that light pulses can be used to induce magnetic moments in materials with what is called helicity or optical spin-moment, which was published in Physical Review Letters.”

Recently his group's calculations of the magnetic spin-moment contributed to the discovery of a method that may lead to faster electronic memories.

“We managed to develop the theory of a small relativistic effect, known as the spin-Hall effect, which has received a lot of attention within spintronics, originally spin-electronics. I was almost surprised that our calculations on platinum and tungsten fit so well with the data measured by our colleagues in Switzerland.”

Despite his research focus, he greatly values his role as a teacher. In recent years, he has taught on average 40 percent of a full-time position. Almost everyone who has studied engineering physics the past 13 years at Uppsala University have had Peter Oppeneer as a teacher in quantum physics. He hopes he can inspire at least some of the students to continue to research.

What advice would you give to students who are interested in your field?

“Start to think about why things are the way they are, and try to find the best explanation for these reasons. Then be prepared to spend a lot of time on deepening your understanding. Then, ask new questions.”

Peter Oppeneer adds:

“It's so important to learn fundamental physics. Expert knowledge in a specific topic is not particularly important because such knowledge quickly becomes outdated. These days, technology changes very quickly.”

Anneli Björkman


Facts Peter Oppeneer

Age: 59
Title: Professor of Materials Theory at the Department of Physics and Astronomy
Education: Docent of Physics at Dresden University, Germany
Family: Married to Maria Oppeneer

Does in his spare time: Study the Bible. When I lived in Darmstadt and Dresden in Germany in the 90's I was a Bible teacher in a parish at evening time, but I don’t do that anymore. How my religious beliefs go together with my scientific approach? We must see that the Bible speaks of such things as soul, spirit, faith. And physics are talking about completely different things like electrons, protons, and neutrons. Physics has no ability to express views on what we call the soul, spirit or faith. On the other hand, the Bible says nothing about neutrons and the like. But the Bible speaks of what is relevant to our lives. That physics cannot do. So I see no contradiction.

Most proud of: I am proud of my team, probably the most when they come to me with their own great research ideas. I’m also happy and proud that I have been able to finance them all entirely with external research grants. The last twelve years, six EU appropriations provided me with the opportunity to develop my own ideas, and to plan and conduct research. The publication of many good articles, including twelve in various Nature journals, has contributed greatly to us getting EU-funding.

Thankful for: My wife Maria who has supported me for many years!

I wanted to be when I was little: I was of a mind at first to become an archaeologist, because I thought it was exciting. However, it could not give me the same challenge as physics and mathematics, nor catch my interest to the same extent. But I am happy that my nephew is about to obtain a doctoral degree in archaeology!

Magnetic order in a two-dimensional molecular chessboard

More about Peter Oppeneer and Uppsala University’s research within materials theory

Anneli Björkman

Last modified: 2022-01-14