Rice-led team finds altermagnetism in ultrathin ruthenium dioxide
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Scientists at Rice University, the University of Minnesota, and the Paul Scherrer Institute have observed altermagnetism in ultrathin films of ruthenium dioxide, a material previously considered nonmagnetic in bulk form. The findings, published in Science Advances, show that lattice strain in films only a few atomic layers thick induces unconventional spin textures. The result suggests strain could be used to control magnetism in future spintronic devices.
Key Facts
- Ruthenium dioxide, previously considered nonmagnetic in bulk form, exhibits altermagnetic spin textures when prepared as an ultrathin film only a few atomic layers thick.
- The study was led by Rice University physicist Ming Yi, with Bharat Jalan of the University of Minnesota and Milan Radovic of the Paul Scherrer Institute, and published in Science Advances.
- The altermagnetic behavior appears only when the ultrathin film experiences lattice strain, which places pressure on the material's atomic structure.
- Researchers used spin-resolved angle-resolved photoemission spectroscopy to measure the spin textures that revealed the unconventional magnetism.
- The strain-dependent nature of the effect suggests lattice strain could be used as a tuning knob to induce or control altermagnetism in next-generation spintronics and RAM architectures.
Altermagnetism in Ultrathin Films
Ruthenium dioxide was one of the first materials proposed as an altermagnetic candidate, but studies on its bulk form did not return evidence of magnetism. The new research shows that its ultrathin form, on the other hand, may be the key in making it magnetic. The team measured spin textures using spin-resolved angle-resolved photoemission spectroscopy, a technique that reveals how electron spins are arranged in space. After analyzing the measurements and informing the interpretation with theoretical calculations, the researchers found spin textures consistent with unconventional magnetism under their experimental conditions.
Strain as a Magnetic Control
The unusual spin behavior appeared only when the electron structure of the ultrathin ruthenium dioxide experienced lattice strain, which places pressure on the material's atomic structure. Without that strain, as in the material's natural bulk form, the electron spins did not show signs of altermagnetism. Yichen Zhang, the first author on the paper and a recent Rice graduate, said the strain-dependent nature suggests lattice strain could be used as a tuning knob to induce or control altermagnetism. Such control could prove valuable for spintronics, a field that uses electron spin as well as electrical charge to process and store information, and for new computer memory designs.
Debate Over Ruthenium Dioxide
The findings highlight how difficult it can be to identify and describe the behavior of quantum materials. The result raises the possibility that researchers could deliberately adjust lattice strain to control magnetic behavior in future electronic materials.
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Rice-led team finds altermagnetism in ultrathin ruthenium dioxide
