By Grace Kim

Researchers have induced spin textures consistent with altermagnetism in ruthenium dioxide by growing the material as an ultrathin, strained film just a few atomic layers thick. The finding, reported August 27, 2026 in Science Advances, marks the first experimental evidence that dimensionality and strain can activate a magnetic state absent from the material's bulk form.

Ruthenium dioxide is a quantum material long considered nonmagnetic in bulk. A multi-year scientific debate over its magnetic properties ended with consensus: bulk RuO2 exhibits no magnetism. The new work overturns that picture when the material shrinks to atomic-scale thickness.

Rice University physicist Ming Yi led the study with Bharat Jalan of the University of Minnesota and Milan Radovic of the Paul Scherrer Institute. First author Yichen Zhang is a recent Rice graduate.

"Ruthenium dioxide was one of the first materials to be proposed as an altermagnetic candidate, but studies on its bulk form didn't return evidence of magnetism," Yi said. "Our research shows that its ultrathin form, on the other hand, may be the key in making it magnetic."

What did the researchers measure?

The team examined the material's spin texture. Spin texture describes how electron magnetic moments arrange in space. Those patterns reveal whether a material is magnetic and what type of magnetism it displays.

The instrument was spin-resolved angle-resolved photoemission spectroscopy. The technique maps both electron energy and spin direction at the surface of a material.

"After analyzing our measurements, including informing our interpretation with theoretical calculations, we found that, in our experimental conditions, the ruthenium dioxide shows spin textures consistent with unconventional magnetism," Zhang said. "This suggests that bulk and ultrathin ruthenium dioxide, under the right conditions, may have distinctly different magnetic properties."

The paper, titled "Observation of mirror-odd and mirror-even spin texture in ultrathin epitaxially strained RuO2 films," lists 28 co-authors across U.S. and European institutions.

Why does strain matter?

The unusual spin behavior appeared only under one condition. The electron structure of the ultrathin film had to experience lattice strain, pressure applied to the material's atomic arrangement.

Without strain, the spins showed no sign of altermagnetism. The unstrained bulk form remained nonmagnetic, consistent with the earlier consensus.

"The strain-dependent nature suggests that we may be able to use lattice strain as a tuning knob to induce or control altermagnetism," Zhang said. "This could be extremely useful when thinking about next-generation spintronics and RAM architectures."

That control knob is the commercial hook. Altermagnetism, a recently proposed magnetic state, could enable computer memory that is smaller, faster and more efficient. Spintronics uses electron spin as well as electrical charge to process and store information. A material whose magnetism can be switched on by engineering strain, rather than by chemistry or temperature, gives device designers a direct fabrication lever.

What comes next?

The result also shows how hard it is to characterize quantum materials. Dimension changes alone produced behavior the bulk material never showed.

"This work shows just how complex these questions can be," Yi said. "The high quality material prep and the careful measurement protocol were critical to our observation of the correct electron spin properties."

Yi noted that the team determined not only the magnetic state symmetries but a potential way to manipulate them in next-generation quantum materials.

Funding came from the U.S. Department of Energy under three grants (DE-SC0026179, DE-SC0020211, DE-SC0024710), the Gordon and Betty Moore Foundation's EPiQS Initiative (GBMF9470) and the Robert A. Welch Foundation (C-2175).

The work remains basic research. No device, memory cell or circuit has been built from strained RuO2. But if lattice strain proves to be a reliable control over altermagnetic states, materials engineers gain a new route to spintronic memory that conventional ferromagnets cannot offer.