Discovery of altermagnetic state in ruthenium dioxide could lead to advancements in computing technologies
Scientists from ECE and the Department of Chemical Engineering and Materials Science have demonstrated magnetism in ultra thin layers of ruthenium dioxide (RuO₂), establishing the potential of its use in advancing spintronic and quantum computing technologies. The details of the study are published in Proceedings of the National Academy of Sciences of the United States in a paper titled “Metallicity and Anomalous Hall Effect in Epitaxially-Strained, Atomically-thin RuO2 Films.”
RuO₂ has previously been a material of interest because of its magnetic properties and therefore possible use in spintronic applications. However, studies so far have offered conflicting results regarding the magnetic moment observed in bulk and thin films of the material. Earlier studies have observed small magnetic moments and more recent studies have observed negligible magnetic moments contradicting the earlier observations. The conflicting results have drawn attention to the varying sample quality across the different studies. In the case of thin films, variations in epitaxial strain among other things can influence the material’s electronic and magnetic properties. Gathering comprehensive transport data on RuO₂ thin film has remained a challenge.
The new study addresses these conflicting results and the related challenges. Using hybrid molecular beam epitaxy the team grew ultrathin epitaxial RuO₂ on a titanium dioxide (TiO₂) substrate. When epitaxial strain was applied on the RuO₂ film, it demonstrated the anomalous Hall effect (AHE) consistently down to the unit cell limit. By pointing to epitaxial strain as the origin of magnetism in RuO₂ thin films, the team’s research has unlocked the possibility of applying the material in next-generation spintronics and quantum technologies. Additionally, the application of strain engineering also broadly demonstrates that materials could show new behaviors when controlled and manipulated at the atomic scale.
Paul Palmberg Professor Tony Low of ECE and Shell Chair Bharat Jalan of the Department of Chemical Engineering and Materials Science were senior authors of the study.
Learn about the details of the discovery and the team who worked on it in the post by the College of Science and Engineering.
Read the paper, “Metallicity and Anomalous Hall Effect in Epitaxially-Strained, Atomically-thin RuO2 Films" on the PNAS website.