Scientists at the University of Notre Dame synthesized a material that exhibits a rare and promising form of magnetism known as altermagnetism, which could reshape how computers store and process information in the future, a new study in Nature Communications shows.

Scientists have long sought out new methods that can support the future of ultra-fast and energy efficient electronics, said Nirmal Ghimire, associate professor in the Department of Physics and Astronomy. Ghimire and collaborators have synthesized single crystals of a compound called called CoNb₄Se₈ that exhibits altermagnetism, according to a recently published paper in Nature Communications.

“This is a brand-new type of magnetism, realized just within the last few years,” said Ghimire, who is affiliated with Notre Dame’s Stavropoulos Center for Complex Quantum Matter.

The most common form of magnetism is ferromagnetism — the type of magnet that can be tacked to a refrigerator or metal cabinet. In this type of magnetism, spins of the electrons align spontaneously in the same direction and stay aligned, making them detectable and easy to manipulate. This type of magnetism is used in present day computers and many other devices.

Another well-known form of magnetism is antiferromagnetism, where the electron spins align in opposite directions, canceling each other out. As a result, this form is difficult to sense and manipulate. However, scientists have found that if they could properly detect and manipulate the antiferromagnets, they would be superior to ferromagnets for electronic devices applications. The result, altermagnetism, would almost be 1,000 times faster — terahertz rather than gigahertz — and need less space to store data.

As seen in the Ghimire’s new material CoNb₄Se₈, altermagnetism combines the best of both worlds, with properties of both ferromagnets and antiferromagnets.

“In electronic band structure, these altermagnets behave like ferromagnets — but in terms of ordering of the spin, they behave like antiferromagnets,” said Resham Regmi, a graduate student in Ghimire’s lab who is the first author on the paper.

CoNb₄Se₈ (a compound of cobalt, niobium, and selenium) is part of a family of compounds that have been known since 1970s, but this particular compound had only been made in polycrystalline, a solid that contains many small crystals.

“The moment we noticed that with a proper spin structure, this can be an altermagnet, we attempted to grow single crystals, and we succeeded in getting high quality crystals that allowed us to investigate its properties,” Ghimire said.

When Ghimire's team cooled the material below -105°C, something unusual happened: spins of cobalt atoms lined up magnetically in a pattern called A-type antiferromagnetism — each atomic layer points in one direction, and the next flips the other way. Researchers then calculated the electronic band structure with this spin structure, and revealed a characteristic property of an altermagnet (and also of a ferromagnet) that is necessary for the next generation of electronics, which will rely on electron spin rather than charge to carry data.

These discoveries mean that engineers could build smaller, faster, cooler-running devices. And because CoNb₄Se₈ has a layered structure, it can be exfoliated in thin flakes — making it perfect for to couple with other materials, Ghimire said.

“You can peel them off, and that allows us to connect these altermagnetic properties with other interesting features — like putting them near superconductors or topological materials. That could lead to more exotic phenomena predicted to be allowed due to altermagnetism,” Ghimire said.

Ghimire began this research after starting work at Notre Dame in 2023, with support from the Army Research Laboratory U.S. Army Research Office. His team collaborated with George Mason University, Argonne and Oak Ridge National Laboratories, to confirm the material’s crystal and magnetic structure using advanced tools.

“There are a lot of predictions out there about altermagnetism, but not many confirmed materials,” Ghimire said. “Being able to make and show that this material really does have this property is very important at this stage.”

Follow-up studies are already in progress.

“The big hope is that one day, we’ll find a material that can operate at terahertz frequencies — and still be energy efficient,” Ghimire said.

Originally published by Deanna Csomo Ferrell at science.nd.edu on May 13, 2025.