SLAC Team Confirms Altermagnetism, a Third Kind of Magnetism, in Manganese Telluride

Physicists have confirmed the existence of a third kind of magnetism, ending a classification of magnetic materials that had stood, in its essentials, for nearly a century. A team led by the United States Department of Energy’s SLAC National Accelerator Laboratory reported on 29 October 2026 that it had delivered conclusive experimental proof of altermagnetism, a magnetic phase that behaves like no magnet known before it, according to SLAC.

The finding, published in the journal Science, settles a question that has been building in condensed-matter physics for several years: whether a class of materials predicted on paper in 2022 is real. The team’s answer, based on experiments with a material called manganese telluride, is yes. The researchers found direct evidence of chirality — a handed, spiral-like twist in the arrangement of the material’s electron spins — that, according to the team, cannot be explained by either of the two established forms of magnetism.

“We believe our results provide robust experimental confirmation that this third phase — altermagnetism — is real,” said lead author Daniel Jost, an associate scientist at SLAC and the Stanford Institute for Materials and Energy Sciences, according to SLAC. Jost said researchers had spent recent years observing phenomena that did not fit neatly into the existing two-way split between ferromagnetism and antiferromagnetism, and had been assembling evidence of a third type that bridges the qualities of both.

The material at the centre of the work, manganese telluride, known by its chemical formula MnTe, was regarded for decades as an ordinary antiferromagnet. The new study shows that it is, in fact, an altermagnet: a material whose electron spins alternate up and down like an antiferromagnet, producing no overall magnetic field, yet which can still generate the spin-polarised electric currents that are the hallmark of a ferromagnet. Those two properties were long thought to be mutually exclusive.

The decisive measurement was made not at SLAC itself but at the European Synchrotron Radiation Facility, known as the ESRF, in Grenoble, France. There, the team took its manganese telluride sample to a beamline called ID32, which is known for producing highly controlled beams of polarised X-rays. By scattering circularly polarised X-rays off the material and comparing how it responded to left-handed and right-handed light, the researchers teased out a clear chiral signal — a signature that should not exist in a conventional antiferromagnet.

“Chiral materials scatter left-handed polarized X-ray beams differently than they do right-handed beams,” Jost explained, according to SLAC. “Non-chiral materials would scatter each beam of light the same way.” The difference the team measured was the missing piece of the puzzle. “This chiral signature gave us the solid experimental ground to say altermagnetism stands in a class of its own,” Jost said.

The experiment was first completed in 2024, and the team repeated it in early 2025, confirming the earlier results before publishing. Rachel Nickel, a postdoctoral scientist at the ESRF who helped design and conduct the experiment on the ID32 beamline, said the technique had confirmed that manganese telluride was genuinely exhibiting altermagnetic properties, according to SLAC. “Altermagnetism was only proposed a few years ago, and the rapid progress in confirming these models is incredible,” she said.

The result matters far beyond the physics laboratory. Altermagnetic materials are candidates for a field called spintronics, in which electronic devices exploit the spin of electrons as well as their charge. According to SLAC, identifying such materials could allow researchers to design advanced electronics with applications including quantum technologies, memory devices and data centres — hardware that could be faster, more robust and far less power-hungry than today’s equivalents.

For now, the discovery is a fundamental one. No altermagnetic device exists yet, and the researchers themselves describe the next stage as exploration: learning how altermagnetic states can be influenced and controlled using light and electricity, and how they might be turned into practical technology. But the confirmation that a third magnetic phase exists at all redraws a map of magnetism that physicists have used since the 1930s, and it gives engineers a new class of material to work with.

Magnetism, in three kinds

To understand why the announcement has excited physicists, it helps to start with what magnetism is. To most people it is a familiar force: the pull that holds a child’s drawing to a refrigerator door, or the tug that turns a compass needle north. To a physicist, magnetism is a quantum property of a material, determined by the behaviour of its electrons.

Every electron carries a property called spin, a form of internal angular momentum that can point either “up” or “down”. In physics, a material counts as magnetic when the spins of its electrons are ordered in a specific pattern, rather than pointing at random. For almost ninety years, that ordering was understood to come in exactly two varieties.

The first, ferromagnetism, is the magnetism of everyday life. In a ferromagnet, all of the electron spins point in the same direction — up, up, up, or down, down, down — and their combined effect creates an observable magnetic field. Humans have known about and used this class of magnets since ancient times: lodestone, a naturally magnetised rock, was used in compasses centuries ago, and the same principle drives the magnets in motors, hard drives and refrigerator doors today.

The second, antiferromagnetism, was discovered in 1933. In an antiferromagnet, neighbouring spins point in opposite directions, alternating up-down-up-down, so that their magnetic effects cancel each other out. The material produces no net magnetic field, and to the outside world it looks non-magnetic, even though its electrons are highly ordered inside.

That two-category system dominated physics for nearly ninety years. But in recent years, researchers began to notice materials that refused to fit into either box. Some materials showed the alternating spin pattern of an antiferromagnet, with no net magnetisation, and yet they also showed effects that only ferromagnets were supposed to show — most importantly, the ability to carry spin-polarised currents, in which electrons of one spin direction dominate the flow.

In 2022, researchers proposed a name for this awkward class: altermagnets. The proposal came from a team including Libor Šmejkal, Jairo Sinova and Tomas Jungwirth, working from the Institute of Physics of the Czech Academy of Sciences and Johannes Gutenberg University Mainz, who published the theoretical framework in the journal Physical Review X. Their idea was that altermagnets share the alternating spin pattern of antiferromagnets, but with a crucial twist: the crystal lattice surrounding the “up” spins is rotated relative to the lattice surrounding the “down” spins. That geometric twist breaks a symmetry in the material, and the broken symmetry is what allows the strange combination of properties.

The theory was elegant, but physics demands evidence. The first direct experimental evidence arrived in February 2024, when an international team led by researchers at the Paul Scherrer Institute in Switzerland published results in Nature showing the predicted spin splitting in manganese telluride, using a technique called angle-resolved photoemission spectroscopy. A press release from Johannes Gutenberg University Mainz at the time described the work as the experimental demonstration of a third branch of magnetism, and noted that the theorists had predicted the new branch in a series of papers beginning in 2019.

That 2024 result was a major step, but it was not the end of the story. Other groups added evidence through 2024, including X-ray imaging of magnetic domains in manganese telluride at the MAX IV Laboratory in Sweden. Even so, as Jost put it, a piece of the puzzle was still missing: direct experimental evidence of chirality in an altermagnetic candidate material. Chirality — handedness — is the property of an object that cannot be superimposed on its mirror image, like a left hand and a right glove. The new Science paper supplies exactly that evidence.

How the experiment worked

The SLAC-led team’s approach was to look for handedness where no handedness should be. In a conventional antiferromagnet, the alternating spins and the surrounding crystal lattice are arranged symmetrically, so the material has no preferred handedness. In an altermagnet, the rotated lattice around the two spin directions gives the material’s magnetic and electronic structure a distinct twist — a chirality that a conventional antiferromagnet lacks.

Chirality is difficult to see directly, but it leaves a fingerprint in the way a material interacts with polarised light. Chiral materials scatter left-handed polarised X-rays differently from right-handed polarised X-rays; non-chiral materials scatter both beams identically. That difference gave the team a clean test.

The team took its manganese telluride sample to the ESRF, one of the world’s most powerful synchrotron light sources, and used its ID32 beamline, which can generate highly controlled polarised X-ray beams. By scattering circularly polarised X-rays from the material and comparing the response to left- and right-handed light, the researchers found a clear chiral signal — one that, according to the team, should not exist in a conventional antiferromagnet.

The paper reporting the result is titled “Chiral altermagnon in MnTe”, and it appeared in Science on 29 October 2026, with the digital identifier 10.1126/science.adv3196. The title refers to an “altermagnon”: a magnon is a quantum of a spin wave, a ripple of magnetic disturbance travelling through a material, and the chiral altermagnon is the distinctive spin-wave signature of the altermagnetic state.

The team’s caution is visible in its method. The initial experiment was completed in 2024, and rather than rushing to publish, the researchers repeated the measurement in early 2025 and confirmed the earlier results. Only then did they present the finding as conclusive proof. That care matters in a field where a claimed new phase of matter invites intense scrutiny, and where earlier claims in neighbouring areas of physics have sometimes failed to survive replication.

The work was supported in part by the United States Department of Energy’s Office of Science, according to SLAC, and it drew on facilities on two continents: the SLAC laboratory in Menlo Park, California, where the team is based, and the ESRF in Grenoble, where the decisive measurement was made.

Why altermagnets could change electronics

The excitement around altermagnetism is not only about taxonomy. It is about what engineers might build with a material that combines the best properties of the two older classes of magnet.

The field that stands to gain most is spintronics. Conventional electronics uses only the charge of the electron to store and move information: a bit is a 1 or a 0 depending on whether charge is present or absent. Spintronics adds a second control knob, the electron’s spin, which can also encode information. Devices built on spin have the potential to be faster, more robust and far less power-hungry than charge-only devices, and that matters enormously in an era when data centres already consume a significant share of the world’s electricity.

Until now, spintronics has been held back by a trade-off between the two known kinds of magnet. Ferromagnets are easy to read — their magnetic field makes their state easy to detect, and they can drive spin currents efficiently — but they are fragile. As Jost explained, ferromagnets are too easily influenced by stray magnetic fields: a permanent magnet in a pocket, carried past a spintronic device built with ferromagnets, could flip its bits and scramble the information stored there.

Antiferromagnets solve that problem, because their cancelling spins make them immune to outside magnetic fields. But they create a new one: they are practically invisible. With no net magnetic field and no easy way to generate spin currents, the information stored in an antiferromagnet is hard to read out.

“Altermagnets combine the best of both,” Jost said, according to SLAC. “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. That gives you an additional degree of freedom to work with.”

That combination is what makes the result interesting to the technology industry. A memory device built from an altermagnet could, in principle, be as stable as an antiferromagnet and as readable as a ferromagnet. A processor built on spintronic logic could switch states with far less energy than a conventional transistor, because flipping a spin takes less energy than moving a charge. And because altermagnets produce no stray magnetic field of their own, devices could be packed more densely without interfering with each other — a valuable property as chipmakers struggle to keep shrinking transistors.

Quantum technologies are another possible beneficiary. Quantum computers and quantum sensors rely on delicate quantum states that are easily disturbed, and the spin-polarised currents that altermagnets can carry are a natural tool for manipulating those states. Data centres, which are under growing pressure over their energy consumption, are a third: if spintronic memory and logic can cut the power drawn by servers, the savings at scale would be large.

None of this exists yet. The researchers are clear that the new paper proves a phase of matter, not a product. Turning altermagnetism into technology will require learning how to switch altermagnetic states reliably, how to read them at speed, and how to manufacture altermagnetic materials at the scale and purity that the electronics industry demands. SLAC says future research will explore how altermagnetic states can be influenced and controlled using light and electricity, to make them more useful in spintronic devices.

Analysis: Why It Matters

1. A ninety-year-old map has been redrawn

The most immediate significance of the result is scientific. Since 1933, every magnetic material without an external field was filed under one of two headings, and textbooks, university courses and engineering handbooks were written around that division. The confirmation of a third heading does not make the old map wrong — ferromagnets and antiferromagnets are still what they always were — but it shows the map was incomplete. That is the kind of result that reshapes a field’s basic vocabulary, and it will filter into teaching, into the way new materials are classified, and into the questions researchers ask when they encounter a material that does not behave as expected. Discoveries of this kind are rare: the last time the classification of magnetism changed, in 1933, the world was still years away from the first electronic computer.

2. Theory moved to proof in four years — unusually fast for physics

The speed of the journey from proposal to proof is striking. The term “altermagnet” was proposed only in 2022, the first direct experimental evidence arrived in 2024, and conclusive proof of the defining chiral signature has now followed in 2026. In condensed-matter physics, where a theoretical prediction can wait decades for experimental confirmation — the Higgs boson took nearly fifty years — a four-year arc from theory to settled fact is remarkable. It reflects two things: a theory that made sharp, testable predictions, and an experimental toolkit — synchrotron X-ray beamlines, photoemission spectroscopy, domain imaging — that was ready to test them. It also reflects a research community that moved quickly once the target was identified, with groups in the United States, Switzerland, France, Sweden, Germany and the Czech Republic contributing evidence within two years.

3. The energy stakes are real, even if the devices are not

It is easy to overstate what a physics paper means for technology, and the honest position is that no altermagnetic chip exists and none is imminent. But the energy stakes behind spintronics are genuine. Data centres already consume roughly one to two per cent of global electricity, and demand is rising fast as artificial intelligence workloads grow — a trend that has dominated technology markets through 2026, with companies spending hundreds of billions of dollars on AI infrastructure. Any technology that can store and process information with substantially less energy is therefore strategically important, not merely academically interesting. Altermagnets are attractive precisely because they attack the problem at its root: flipping a spin, in principle, costs less energy than shuttling charge through a transistor. The new result does not guarantee that saving, but it puts a real material on the table for engineers to test, which is the necessary first step.

4. The experiment is a model of careful, replicable science

The way this result was produced deserves attention in its own right. The team ran its experiment in 2024, repeated it in early 2025, and only then published — a discipline that protects against the false dawns that have embarrassed physics before. The evidence also rests on more than one technique: the 2024 Nature paper used photoemission to show spin splitting, other groups used X-ray imaging to map magnetic domains, and the new Science paper uses polarised X-ray scattering to show chirality. Three different windows onto the same material, all pointing the same way, make the conclusion far harder to dismiss than any single measurement would. In an era when public trust in science depends on visible rigour, that layered, patient approach is itself part of the story, and it is one reason the claim of “conclusive” proof is being taken seriously rather than treated as hype.

5. Europe’s big-science infrastructure made it possible

The geography of the discovery is also worth noting. The lead team sits at SLAC in California, but the decisive measurement was made at the ESRF in Grenoble, using a specialised beamline that few facilities in the world can match. The 2024 evidence came from the Paul Scherrer Institute in Switzerland and the MAX IV Laboratory in Sweden. Altermagnetism was confirmed, in effect, by a network of large public research infrastructures spanning two continents — the kind of shared scientific capacity that no single company or university could build alone. That matters at a moment when governments are debating the value of funding such facilities: the return on a synchrotron is not only the papers it produces, but the new industries those papers can seed, years later. The ESRF’s ring, visible in the photograph accompanying this article, is where a theoretical idea became a measured fact.

What to Watch Next

1. Peer response and replication. The Science paper will now face scrutiny from other groups, who will test the chiral signature in manganese telluride and look for it in other candidate altermagnets. Watch for independent confirmations, and for any challenges to the interpretation, in the coming months.
2. New altermagnetic materials. Manganese telluride is the proof of principle, not necessarily the best material for devices. Researchers will now hunt for other altermagnets — including ones that work at room temperature, are easy to grow as thin films, and can be integrated with silicon manufacturing.
3. Switching and control. The next scientific milestone is demonstrating that an altermagnetic state can be flipped reliably with an electric current or a pulse of light, and read back at speed. SLAC says future work will explore control by light and electricity; the first convincing switching demonstration will be a major story in its own right.
4. First prototype devices. Watch for laboratory demonstrations of altermagnetic memory cells or logic elements, and for partnerships between university groups and semiconductor companies. A working prototype, even a slow one, would move altermagnetism from physics journals into engineering roadmaps.
5. Funding and strategy. Governments and chipmakers deciding where to place long-term bets on post-transistor computing will be watching this field. Expect altermagnetism to feature in research funding calls and in the strategies of companies working on spintronics, memory and quantum hardware.

Sources

• Daniel Jost et al., “Chiral altermagnon in MnTe”, Science (2026) — the peer-reviewed paper reporting the result
• Phys.org — “Confirming altermagnetism: A geometric twist offers experimental proof” (30 October 2026)
• Nanowerk — “X-ray measurements confirm altermagnetism, a third form of magnetism” (30 October 2026)
• Johannes Gutenberg University Mainz — “Scientists directly observed altermagnetism” (19 February 2024)
• Quantum Zeitgeist — “New Magnetic Phase Could Boost Quantum Tech And Data Centers” (29 October 2026)