A research team from the University of Minnesota Twin Cities recently published significant results in the Proceedings of the National Academy of Sciences, observing novel magnetic behavior in ultrathin ruthenium dioxide (RuO₂) material for the first time. This breakthrough discovery opens new material selection pathways for developing next-generation spintronic devices and quantum computing technologies.

The research team used advanced hybrid molecular beam epitaxy technology to successfully fabricate ultrathin RuO₂ films only two unit cells thick (less than 1 nanometer). By precisely controlling epitaxial strain (similar to stretching or compressing a rubber band), the researchers successfully induced magnetic properties in this traditionally non-magnetic metallic material. "This is not only the first experimental confirmation of alternating magnetic states in ultrathin RuO₂, but more surprisingly, we found it to be the most metallic among all oxide materials to date, with performance comparable to elemental metals and two-dimensional materials, second only to graphene," said project leader Bharat Jalan, professor in the Department of Chemical Engineering and Materials Science at the University of Minnesota.

The most critical discovery in the study was the observation of the anomalous Hall effect—the phenomenon where current deflects under a magnetic field—which is an important characteristic for developing new memory and data storage devices. First author Dr. Seunnggyo Jeong noted: "Typically, achieving this effect in metallic RuO₂ requires extremely strong magnetic fields, but we observed it in ultrathin materials with much weaker fields. This material not only maintains excellent structural stability but also has superior metallic properties, allowing direct integration into practical devices."

The research team confirmed through theoretical calculations that strain regulation alters the internal structure of RuO₂ in a specific way, thereby generating new magnetic properties. Tony Low, professor in the Department of Electrical and Computer Engineering, explained: "Our calculations show that strain fine-tunes the material's electronic structure just right, making this magnetic behavior possible." This ability to precisely control material properties at the atomic scale lays the foundation for developing more miniaturized, low-power quantum computing devices.

The study is an international collaboration between the University of Minnesota, MIT, Gwangju Institute of Science and Technology, and Sungkyunkwan University. The research team plans to further explore how to combine strain and layering techniques to design more novel material properties, with the ultimate goal of developing platform materials suitable for future quantum computing, spintronics, and low-power electronics applications.