After 90 Years, Physicists Confirm a Third Type of Magnetism Is Real

That combination shouldn't have existed. In 2022, researchers coined the term "altermagnets" for the proposed third class.

The difference lies in the crystal structure. Altermagnets alternate their spins, but the crystal lattices around oppositely aligned spins are rotated relative to each other. That rotation breaks a symmetry conventional antiferromagnets possess, and it changes how electrons behave.

"By 2024, there were some factors that spoke strongly in favor of altermagnetism being real," Jost said, "but there was still a missing piece to the puzzle."

The missing piece was chirality.

How did the X-rays prove it?

Chirality is "handedness" — like your left and right hands, mirror images that can't be superimposed on each other. A chiral magnetic structure should interact differently with left-handed and right-handed forms of light.

The team ran experiments at the European Synchrotron Radiation Facility (ESRF) in France, using the ID32 beamline, which produces precisely controlled circularly polarized X-rays. These are X-rays whose electric fields rotate in either a left-handed or right-handed direction as the light travels.

"Chiral materials scatter left-handed polarized X-ray beams differently than they do right-handed beams," Jost explained. "Non-chiral materials would scatter each beam of light the same way."

Manganese telluride scattered the two polarizations differently. That chiral response is exactly what altermagnetism predicts and what a conventional antiferromagnet cannot produce.

"This chiral signature gave us the solid experimental ground to say altermagnetism stands in a class of its own," Jost said.

The researchers first ran the experiment in 2024, then returned in early 2025 and reproduced the results — a replication step that strengthened the case considerably.

"This technique helped us confirm that manganese telluride was really exhibiting altermagnetic properties," said co-author Rachel Nickel, a postdoctoral scientist at ESRF who helped design and run the beamline experiment. "Altermagnetism was only proposed a few years ago, and the rapid progress in confirming these models is incredible."

Why could this matter for computers?

The finding matters for spintronics, a field that builds devices using electron spin in addition to electrical charge. Both traditional magnet types have held the field back.

"Ferromagnets are too easily influenced by magnetic fields," Jost said. A magnet in your pocket walking past a ferromagnetic spintronic device could flip its bits and scramble stored data. "Antiferromagnets fix that problem, but they are practically invisible — so you can't easily read the data stored in them or use them to drive efficient spin currents."

Altermagnets, in principle, offer the best of both. Their opposing spins cancel out, so stray magnetic fields can't easily disturb them. At the same time, their unusual electronic structure lets them generate spin-polarized currents that can be read out.

"Altermagnets combine the best of both," Jost said. "They have zero net magnetization, so they're stable, but they still have the capability to generate spin-polarized currents needed to easily extract information."

The researchers' next step is learning to control altermagnetic states with external influences such as light and electricity. Practical devices remain years away, and the team cautions that significant development is still needed. Still, the confirmation establishes a firmer experimental foundation for future work on faster computer memory, more energy-efficient data centers, and quantum technologies.

In plain terms: a third class of magnetic materials is now official, and engineers have a new set of ingredients to build with.