Physicists have long debated the magnetic nature of ruthenium dioxide. While this metallic oxide serves as a standard industrial catalyst and provides strong electrical conductivity, experimental results regarding its magnetic state have remained contradictory. Some trials suggested the material functions as an altermagnet, which is a state combining properties of magnets and nonmagnetic materials. Other tests on bulk crystals found no magnetic evidence at all, leading to confusion in the scientific community.
New research indicates that the inconsistency stems from how the material is handled at the atomic level rather than the material itself. By growing ruthenium dioxide films at a thickness of only two nanometers and applying epitaxial strain, researchers detected distinct magnetic order. This indicates that magnetism in this substance is not a fixed attribute but a condition that changes based on the crystal structure.
To achieve these results, the team grew ultrathin films on titanium dioxide substrates. Because the atomic spacing of the substrate differs from the film, the material stretches to fit the surface. This mechanical stress shifts the positions of atoms, which alters electron interactions. Using spin-resolved angle-resolved photoemission spectroscopy, the researchers mapped the spin and momentum of electrons to identify the hidden signal.
This study provides evidence that strain serves as a control mechanism for magnetic properties in materials previously thought to be nonmagnetic. While these experiments took place at low temperatures, the ability to trigger magnetism through lattice engineering offers a path toward energy-efficient electronics. Future work will determine if this magnetic state can persist at higher temperatures for practical hardware integration.