After 90 Years of Two Kinds of Magnetism, SLAC Scientists Prove a Third Exists

For nearly 90 years, physics textbooks have described two kinds of magnetism that materials show on their own. A team led by the U.S. Department of Energy’s SLAC National Accelerator Laboratory now says it has conclusive experimental proof of a third: altermagnetism. The findings, published in the journal Science, show a telltale “handedness” in the magnetic behavior of manganese telluride that conventional magnets cannot produce.

The result matters beyond the lab. Altermagnets could help engineers build faster, more stable and more energy-efficient memory and computing hardware, an appealing prospect as AI data centers strain power grids.

What altermagnetism is

Magnetism, to a physicist, is about how electrons’ spins line up. In ferromagnets, the kind that hold art to a refrigerator, all the spins point the same way and produce an outside magnetic field. In antiferromagnets, identified in 1933, spins alternate up and down and cancel each other out, so the material shows no net magnetism, SLAC explained.

In recent years, researchers noticed materials that did not fit either box. They had alternating spins and no net magnetization, like antiferromagnets, but could carry spin currents, like ferromagnets. In 2022, researchers proposed the term “altermagnets” for this class. The proposed explanation is a geometric twist: the crystal lattice around the “up” spins is rotated relative to the lattice around the “down” spins.

How the SLAC team found the proof

“By 2024, there were some factors that spoke strongly in favor of altermagnetism being real,” lead author Daniel Jost, an associate scientist at SLAC and the Stanford Institute for Materials and Energy Sciences, said in the lab’s announcement, “but there was still a missing piece to the puzzle.”

That missing piece was chirality, the property that makes a left hand impossible to fit into a right-handed glove. An altermagnet’s twisted lattice should give its magnetic structure a handedness that ordinary antiferromagnets lack. To test it, the team took manganese telluride, long classified as an antiferromagnet, to the ID32 beamline at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France, which produces tightly controlled polarized X-ray beams.

“Chiral materials scatter left-handed polarized X-ray beams differently than they do right-handed beams,” Jost said. “Non-chiral materials would scatter each beam of light the same way.” By comparing the two, the researchers found a clear chiral signal in the material’s magnetic waves, known as magnons, that should not exist in a conventional antiferromagnet. The paper’s title, “Chiral altermagnon in MnTe,” names that signal.

The first experiment was completed in 2024, and the team repeated it in early 2025 with the same result, ScienceDaily reported. “Altermagnetism was only proposed a few years ago, and the rapid progress in confirming these models is incredible,” said co-author Rachel Nickel, a postdoctoral scientist at ESRF who helped design and run the experiment.

Why it matters for chips and data centers

The discovery feeds into spintronics, a field that uses both an electron’s charge and its spin to store and move information. Spintronic devices could be faster, sturdier and far less power-hungry than today’s electronics, according to SLAC.

Each older type of magnet has a drawback. “Ferromagnets are too easily influenced by magnetic fields,” Jost said. “If you have a permanent magnet in your pocket and walk by a spintronic device built with ferromagnets, you could start flipping the bits, scrambling the information stored there. Antiferromagnets fix that problem, but they are practically invisible.”

“Altermagnets combine the best of both,” he 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.”

Lower-power hardware would land in an industry where energy is now a central constraint. Developers are making unusual promises to win grid access, such as OpenAI’s offer to cut up to 1,000 megawatts at a Georgia campus when the grid is strained, and chip suppliers are racing to cut power use, as Marvell’s $115 billion bet on Lumentum’s AI optics shows.

What comes next

The finding is basic science, and no altermagnetic memory chip is on the market. SLAC said the next step is learning how altermagnetic states can be influenced and controlled with light and electricity, which would be needed before the materials could be used in quantum technologies, memory devices or data centers. The research was supported in part by the DOE Office of Science.

For a field that spent nine decades with two categories, the paper marks a shift. “This chiral signature gave us the solid experimental ground to say altermagnetism stands in a class of its own,” Jost said.

Sources

• Jost et al., “Chiral altermagnon in MnTe,” Science (Oct. 29, 2026)
• SLAC: SLAC researchers find proof of altermagnetism, a new magnetic phase
• ScienceDaily: SLAC scientists find conclusive proof of a mysterious third type of magnetism
• arXiv preprint: Chiral altermagnon in MnTe