Just 1% strain exposes hidden magnetism, opening new way to control electrical signals

Rice University researchers have found a way to isolate a single magnetic domain in manganese telluride, giving them a clearer view of its magnetic structure and a new way to control an electrical effect in the material. The work focuses on altermagnetism, a recently recognized form of magnetism that could offer a different route to spin-based electronics. Researchers are interested in altermagnets because they may combine useful properties of ferromagnets and antiferromagnets while potentially enabling faster, lower-heat information processing. The challenge is that manganese telluride normally forms multiple magnetic domains, which can point in different directions. Their signals can overlap, making it difficult to determine the material’s intrinsic magnetic structure. The Rice team addressed the problem by applying uniaxial strain, stretching the manganese telluride in one direction. This forced the material into a single-domain state that could be measured more clearly. “Altermagnets like hexagonal manganese telluride typically form multidomain structures where the magnetic forces divide into separate equivalent domains that spin in different directions to satisfy the underlying threefold rotational symmetry of the hexagonal lattice,” said Dai, the Sam and Helen Worden Professor of Physics and Astronomy. “The signals from these coexisting domains could overlap, making it hard to know what the underlying magnetic structure actually is. Here, we were able to apply a uniaxial strain, which resulted in a single magnetic domain we could clearly resolve into the underlying magnetic structure.” The single-domain state also allowed the researchers to observe a sharp feature in the material’s anomalous Hall effect, which produces a voltage across a material when electrical current flows through it and is influenced by its magnetic properties. At about 230 kelvin, or minus 45 degrees Fahrenheit, the researchers found that strain could change the polarity of this Hall signal. The electrical response could therefore be switched without substantially changing the material’s underlying magnetic interactions. “By applying the uniaxial strain, we were able to finally resolve the magnetic structure of manganese telluride,” said Sijie Xu, a Rice graduate student and co-first author. “This also allowed us to see a remarkably sharp feature in the anomalous Hall signal, which describes a lateral voltage generated when an electrical current flows through the material due to its magnetic structure.” Strain offers temperature alternative The researchers believe the tunability comes from changes in the material’s Berry curvature, a property that describes how electrons behave as they move through a material’s electronic structure. The scale of the required strain is also significant. The team’s calculations suggest that a 1% change in strain could produce an effect equivalent to changing the temperature by about 150 kelvin. Temperature is commonly used to tune magnetic properties, but that approach is difficult to apply in practical electronics. Mechanical strain could provide another control mechanism if it can eventually be incorporated into devices. “Essentially, we can use this uniaxial strain to tune the anomalous Hall effect, switching it from one charge to another,” said Zhaoyu Liu, co-first author and researcher in Dai’s group. “Because the magnetic interactions remain largely unchanged, the effect likely originates from strain-induced changes in the Berry curvature.” The researchers see the result as an early step toward using altermagnets in spin-transport technologies, including future memory and high-frequency electronics. “This work brings us one step closer to controlling altermagnets for next-generation spin-transport applications,” Dai said. The study was published in Physical Review X. Recommended ArticlesGet the latest in engineering, tech, space & science - delivered daily to your inbox.With over a decade-long career in journalism, Neetika Walter has worked with The Economic Times, ANI, and Hindustan Times, covering politics, business, technology, and the clean energy sector. Passionate about contemporary culture, books, poetry, and storytelling, she brings depth and insight to her writing. When she isn’t chasing stories, she’s likely lost in a book or enjoying the company of her dogs.