Researchers at the U.S. Department of Energy’s SLAC National Accelerator Laboratory have experimentally confirmed altermagnetism, establishing a third recognized magnetic phase distinct from ferromagnetism and antiferromagnetism. Published in Science, the findings deliver conclusive proof of a phenomenon first proposed in 2022, and directly observe chirality, an asymmetric, spiral-like magnetic structure, within manganese telluride (MnTe). Identifying these materials could enable advances in quantum technologies, memory devices and data centers.

Altermagnetism Emerges: Beyond Ferromagnetism and Antiferromagnetism

This confirmation, coming just four years after the initial postulate, highlights a rapid pace of advancement in the field of magnetism. The team used advanced techniques to visualize this chiral signature, solidifying the classification of altermagnetism as a unique magnetic state. The unique properties of MnTe stem from its ability to exhibit characteristics of both ferromagnetic and antiferromagnetic materials simultaneously.

Antiferromagnets, with their canceling electronic spins, offer stability but lack the easily readable signal of ferromagnets; altermagnets, however, possess zero net magnetization while retaining the capacity to generate spin-polarized currents. “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,” explains Daniel Jost, Associate Scientist at SLAC and Stanford Institute for Materials and Energy Sciences.

“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, by contrast, offer a potential solution to both issues, providing stability and readability. Initial experiments demonstrating these properties were completed in 2024, with confirmatory trials following in early 2025.

Rachel Nickel, postdoctoral scientist with ESRF, contributed to the experimental design and execution on the ID32 beamline, helping to validate the altermagnetic characteristics of manganese telluride. The rapid confirmation of altermagnetism, as noted by researchers, is particularly noteworthy.

By 2024, there were some factors that spoke strongly in favor of altermagnetism being real.
Daniel Jost, associate scientist at SLAC and Stanford Institute for Materials and Energy Sciences

Manganese Telluride Confirmed as Altermagnetic Material

Researchers at SLAC National Accelerator Laboratory directly observed this asymmetric magnetic structure, a spiral-like arrangement of spins, using advanced X-ray scattering techniques. This geometric twist, or chirality, is a break in symmetry that distinguishes altermagnets from conventional antiferromagnets, which lack this defining characteristic. “This chiral signature gave us the solid experimental ground to say altermagnetism stands in a class of its own,” stated lead researcher, Jost.

Initial experiments suggesting altermagnetic properties in MnTe were completed in 2024, but the team needed to confirm the presence of chirality to solidify their findings. The team repeated the experiment in early 2025, validating the initial observations and strengthening the case for MnTe as a true altermagnet.

The technique employed used the way chiral materials interact with polarized X-ray beams; chiral materials scatter left-handed polarized X-ray beams differently than they do right-handed beams, revealing the material’s handedness. “This technique helped us confirm that manganese telluride was really exhibiting altermagnetic properties,” Nickel explained. Prior to this work, scientists had observed magnetic behaviors that did not fit neatly into the established categories of ferromagnetism and antiferromagnetism.

“In the past few years, scientists have observed phenomena that don’t fit neatly into the ferromagnetism-antiferromagnetism dichotomy,” the team reported. This discovery opens new avenues for exploring materials with tailored magnetic properties and could have significant implications for future technologies.

This chiral signature gave us the solid experimental ground to say altermagnetism stands in a class of its own.
Daniel Jost, associate scientist at SLAC and Stanford Institute for Materials and Energy Sciences

Chirality Detection Validates Altermagnetic Spin Structure

Researchers confirmed that manganese telluride exhibits properties of both ferromagnetism and antiferromagnetism, solidifying its status as an altermagnet and establishing a third recognized magnetic class. The team’s results demonstrated direct experimental evidence of chirality, an asymmetric magnetic structure, within the spins of the material, a key indicator of altermagnetism previously missing from the evidence base. Unlike antiferromagnets, which lack this structural twist, altermagnetic materials exhibit a unique response to polarized light, a characteristic the team found to be key for confirmation.

“Non-chiral materials would scatter each beam of light the same way,” explained Jost, highlighting the technique’s ability to differentiate between subtle magnetic states. The team investigated MnTe, a material previously categorized as antiferromagnetic, but recently suspected to be altermagnetic, to test this principle.

The discovery of chirality within MnTe provides strong experimental confirmation that this third phase, altermagnetism, is real, according to Jost, and offers an important validation of the theoretical framework underpinning this new magnetic state. This finding not only confirms a new magnetic phase but also provides a pathway for identifying other materials exhibiting similar properties.

This technique helped us confirm that manganese telluride was really exhibiting altermagnetic properties.
Rachel Nickel, postdoctoral scientist with ESRF, a co-author who helped design and conduct the experiment

Altermagnetism’s Potential for Spintronic Advancements

Altermagnetism offers a potential solution to limitations inherent in both ferromagnetic and antiferromagnetic materials for spintronic applications, promising devices less susceptible to external magnetic interference. Unlike ferromagnets, easily disrupted by stray fields, altermagnets maintain stability while also avoiding the near-invisibility of antiferromagnets that hinders data reading. The unique magnetic arrangement within altermagnetic materials, a chiral, spiral-like structure, is key to their potential. This chirality, directly observed in manganese telluride, provides a distinct signature differentiating altermagnetism from other magnetic phases.

The team’s experiments, initially completed in 2024 and repeated in early 2025, demonstrated this structural twist, confirming the material’s response to polarized x-ray beams in a way neither ferromagnets nor antiferromagnets would. Beyond fundamental physics, this discovery has implications for the development of faster, more robust and energy-efficient spintronic devices.

Traditional computing relies on electron charge. Spintronics uses both charge and spin, offering increased control. “Ferromagnets are too easily influenced by magnetic fields,” Jost elaborated, highlighting a critical drawback for data storage. Altermagnetic materials, by combining the benefits of both ferromagnetic and antiferromagnetic properties, could overcome this challenge. Future work will focus on manipulating altermagnetic states with light and electricity.