Dr. Jeffrey G. Rau received the Herzberg Medal at the 2026 Canadian Association of Physicists Congress.
By Sara Elliott
His mother may not fully grasp what he does for a living, but theoretical condensed matter physicist Dr. Jeffrey G. Rau (BSc ‘08) is in global demand for his expertise in quantum magnetism.
The University of Windsor researcher does not run experiments in a lab. Instead, he builds mathematical and computational models to understand and predict how magnetic materials behave at the atomic level.
“I've always subscribed to the philosophy that pretty much everything is interesting, if you look at it closely enough,” he says.
Since joining the University of Windsor in 2019, Rau has built an international reputation, including collaborating with theoretical and experimental physicists across Canada, the United States and Europe.
In May, Rau was named the winner of the 2026 Canadian Association of Physicists Herzberg Medal in Physics for his work on frustrated magnetism and his contributions to the emerging field of altermagnetism. The medal recognizes significant contributions to physics done in Canada by an early-career physicist.
As his collaborators investigate real materials, they often call on Rau to help interpret complex data using his theoretical expertise. His contributions have helped develop a deeper understanding of these newly discovered materials.
“If they have a brand‑new material, they might not know where to start,” he says.
“Connecting to an underlying theoretical interpretation or answering the broader question of what you do when you start from scratch in understanding some magnetic material can be challenging.”
Rau is strongly motivated by experiment, although the problems that interest him may not necessarily have immediate practical application.
“Usually there is a real chunk of material out there with unexpected properties that someone's trying to understand. That's what typically motivates the kinds of questions I'm trying to answer.”
His publications use a combination of sophisticated analytical and computational methods to tackle complex magnetic phenomena.
Much of his research focuses on frustrated magnetic systems, materials where magnetic interactions compete in ways that prevent atoms from aligning in a simple pattern.
“Usually that means you can get interesting physics,” says Rau. “They’re good places to look for weird and exotic kinds of magnetism or phases of matter.”
Rau often helps analyze data collected through neutron scattering experiments, one of the most powerful and comprehensive techniques for studying magnetic structure.
“If you want to know what's happening in a magnetic material at the atomic level, you want someone to do a neutron scattering experiment on it,” he says.
“They can see how things are changing in space and time and get a lot of information about how the atoms are behaving magnetically.”
Neutron scattering complements X‑ray imaging techniques.
“X‑rays can tell you where the atoms are, but they don’t really see magnetism as easily,” he says.
“Neutrons have a magnetic moment themselves, so they react differently depending on whether the spin of the atom is pointing up or down. They can see magnetic structure at the atomic scale.”
Rau’s theoretical calculations can be critical to these experiments, which often involve months of analysis and require access to expensive, highly competitive international facilities.
Most recently, Rau entered the vigorous scientific debate surrounding a recently discovered magnetic phenomenon known as altermagnetism. His research caught the attention of the editors of the journal Physical Review Letters, where his publication was selected for the Collection of the Year 2024 – a distinction given to about 2% of the papers they publish each year.
Historically, physicists identified two dominant forms of magnetism, ferromagnetism and antiferromagnetism. The former sticks to your fridge, while in the latter, atoms are arranged so their magnetic fields cancel out and thus do not stick to objects.
However, a new class of magnetism, altermagnetism, was first recognized in 2022, challenging long‑standing assumptions about how to classify magnetic behaviour.
“Antiferromagnets were predicted almost 100 years ago and experimentally confirmed in the early 1950s. So the idea that there was something new that had been missed was surprising,” says Rau.
“That’s been part of my motivation beyond the fundamental science itself, that there might be some interesting corner of magnetism that could have been figured out in the 1960s but wasn’t.”
Altermagnetism appears to combine the advantages of both ferromagnetism and antiferromagnetism. These materials can be manipulated almost as easily as ferromagnets while, like antiferromagnets, they do not produce stray magnetic fields.
“Altermagnets are kind of the best of both worlds for some applications,” he says.
“For me, there were some interesting basic physics questions that came up, not only how did we miss these things, and where do they fit into what we already know. That’s what our work tried to clear up.”
The discovery has also generated excitement in the field of spintronics, where magnetic or spin currents replace electrical currents. Electrical currents generate heat, which wastes energy, depletes battery life and raises operating costs.
“Generally, these spin currents have less dissipation, so they help reduce the heat generated,” he says.
“If you could replace charge currents with these kinds of spin or magnetic currents, which suffer less from this kind of dissipation, it could increase efficiency.”
Researchers are also exploring niche future applications in areas such as quantum computing, where excess heat remains a significant challenge at cryogenic temperatures.
“But it’s an ambitious goal, because you’re competing with 80 years of development in semiconductors and an enormous amount of investment over that time,” says Rau.
His work has earned recognition through high‑impact publications, invited talks and lectures and involvement in a wide range of international collaborations. Rau will officially receive the Herzberg Medal at the 2026 Canadian Association of Physicists Congress, where he will deliver a talk June 23 at the University of Ottawa.
“At the heart of it, it's a puzzle,” he says. “It's an interesting puzzle, a real one that exists out there in the world, that you get to throw everything you have at.”