Third magnetism confirmed in manganese telluride tests

A team led by the United States Department of Energy's SLAC National Accelerator Laboratory has confirmed third magnetism in manganese telluride, according to findings published in Science. The result gives experimental backing to a form of magnetic order proposed in 2022, after decades in which physics recognised only ferromagnetism and antiferromagnetism as magnetic phases that occur without an external influence.

The distinction rests on how electron spins line up inside a material. In a ferromagnet, the spins point in the same direction and produce a magnetic field that can be observed directly. That behaviour is familiar from an ordinary fridge magnet and a compass needle. In an antiferromagnet, neighbouring spins alternate, so their effects cancel and the material shows no net magnetic field. Researchers discovered that second pattern in 1933, and the existing picture held for nearly nine decades.

Altermagnets sit between those descriptions. Their spins also alternate, so they show no net magnetization. At the same time, the crystal lattice around spins pointing in one direction is rotated relative to the lattice around spins pointing in the opposite direction. That geometric twist changes the electronic structure and allows spin-polarized currents of the kind usually linked with ferromagnets. The combination had been predicted in theory, but a decisive experimental test was missing.

Lead author Daniel Jost, an associate scientist at SLAC and the Stanford Institute for Materials and Energy Sciences, said the team now has experimental confirmation that the phase is real. The work was reported by Phys.org, drawing on the SLAC announcement and the paper in Science, titled "Chiral altermagnon in MnTe".

The twist that settled the question

The missing evidence was chirality, a property often described as handedness. A chiral structure cannot be superimposed on its mirror image, in the same way a left hand cannot fit a right-handed glove. An ordinary antiferromagnet should show no such handedness in its magnetic structure. An altermagnet, by contrast, should carry a chiral signature because of the rotated lattice around its alternating spins.

To look for that signature, the team took the material to the European Synchrotron Radiation Facility in France. There, on a beamline built to produce highly controlled polarized X-ray beams, the researchers scattered circularly polarized X-rays from the sample and compared how it responded to left-handed and right-handed light. A non-chiral material would scatter each beam in the same way. The sample scattered them differently, revealing a chiral signal that should not exist in a conventional antiferromagnet.

Jost described that signal as giving the team solid experimental ground for placing altermagnetism in a class of its own. The initial experiment was completed in 2024, and the team repeated it in early 2025 to check the result. Rachel Nickel, a postdoctoral scientist at the European Synchrotron Radiation Facility who helped design and run the experiment, said: "Altermagnetism was only proposed a few years ago, and the rapid progress in confirming these models is incredible."

The choice of material mattered. For decades, manganese telluride was treated as an antiferromagnet. In recent years, researchers began to suspect that it belonged to the new class instead, which made it a natural candidate for a test that could separate the explanations. The X-ray result now supports the newer classification, and it does so by measuring a property that the older explanation cannot account for.

Why the result matters for electronics

The finding has drawn attention from researchers working on spintronics, a field that uses both the charge of an electron and its spin to store and move information. Traditional computing uses charge alone. Adding spin gives engineers another control variable, and devices built on that principle have the potential to run faster, prove more resistant to disturbance, and use less power in computing and data centres.

Progress in spintronics has been limited by the trade-offs of the older magnetic classes. Ferromagnets are easy to read and easy to drive with spin currents, but they are also easy to disturb. Jost noted that a permanent magnet carried past a ferromagnet-based device could flip stored bits and scramble information. Antiferromagnets avoid that weakness because they have no net magnetization, yet that same property makes the data stored in them hard to read and hard to use for efficient spin currents.

Altermagnets offer a way around that trade-off, at least in principle. They have zero net magnetization, so they are stable against stray magnetic fields, while still generating the spin-polarized currents needed to extract information. That pairing is the reason researchers see potential applications in quantum technologies, memory devices and data centres, although those applications remain research goals rather than finished products.

Future work will examine how altermagnetic states can be influenced and controlled with light and electricity, according to the research team. Those experiments will test whether the properties seen in the laboratory can be switched reliably and built into devices. Until that work is done, the confirmed result stands as a fundamental advance in how magnetism is classified, with a clear direction for applied research rather than a claim about a device ready for sale.

The speed of the confirmation is itself notable. A phase proposed in theory only a few years ago has now passed a test designed to distinguish it from its closest alternative. For a field that kept the same categories for most of a century, that change in the textbook picture is the story: a material long filed under an old label has provided the evidence for the new classification, and the next question is what engineers can build once its behaviour can be controlled.