Scientists Just Found a New World of Magnetism We’ve Never Seen Before

2 min readFor the past few decades, the world of magnetism seemed scientifically simple. Materials fit into only two groups, ferromagnets and antiferromagnets—end of discussion. Over the past few years, though, that tidy picture has started to crack. Discussion of a third type of magnetism, dubbed “altermagnetism,” has grown from a whisper to a near-consensus. Still, one crucial piece of experimental proof was missing.Now, thanks to scientists at the SLAC National Accelerator Laboratory at Stanford University, that final piece is finally in place.First, a quick refresher. Ferromagnetism and antiferromagnetism, as their names suggest, are two sides of the same coin. In ferromagnets, all electronic spins point the same direction, creating an easily observable net magnetic field. The counterpart is the exact opposite: antiferromagnets containing alternating electronic spins that effectively cancel each other out, producing no net magnetic effect at all. Now, if you had to wager on where altermagnetism fits into this picture, somewhere between these two extremes might be your guess—and you’d be right.“In the past few years, scientists have observed phenomena that don’t fit neatly into the ferromagnetism-antiferromagnetism dichotomy,” Daniel Jost, a SLAC associate scientist and lead author of the new study published in Science, said in a press statement. “Researchers have been compiling evidence of a third type of magnetism that bridges the qualities of these two classes. We believe our results provide robust experimental confirmation that this third phase—altermagnetism—is real.”For decades, scientists have noticed that some materials don’t fit into the simple dichotomy between ferromagnetism and antiferromagnetism. That’s because altermagnetic materials, such as manganese telluride (MnTe), exhibit properties of both. Like antiferromagnets, their spins alternate and cancel out, but like ferromagnets, they can still carry spin currents. In 2022, scientists finally put a name to this phenomenon, and two years later, further proof of its existence emerged.To experimentally demonstrate the existence of altermagnetism, the authors of the new study brought samples of MnTe (once thought to be antiferromagnetic) to the European Synchrotron Radiation Facility (ESRF) to investigate the material’s chirality, or “handedness.” Understanding chirality is key to delineating between altermagnets and antiferromagnets because both have alternating spins (and thus no net magnetism), but a twist in MnTe’s lattice would provide a distinctive chirality. ESRF then fired polarized x-ray beams at the sample and scientists analyzed the results.“Chiral materials scatter left-handed polarized X-ray beams differently than they do right-handed beams. Non-chiral materials would scatter each beam of light the same way,” Jost said in a press statement. The results showed a chiral signal that doesn’t exist in antiferromagnets. The team first produced these results in 2024 and confirmed them the following year. “This chiral signature gave us the solid experimental ground to say altermagnetism stands in a class of its own.”That combination could make altermagnets a key ingredient in future quantum tech and memory devices. They’re as stable as antiferromagnets, with no net magnetization to cause trouble, but like ferromagnets, they still let engineers read and write data. As Jost says, “altermagnets combine the best of both worlds.”Darren lives in Portland, has a cat, and writes/edits about sci-fi and how our world works. You can find his previous stuff at Gizmodo and Paste if you look hard enough.