Researchers from The University of Osaka stabilize an exotic cobalt-based honeycomb structure that could help advance low-cost quantum technologies

Osaka, Japan – Honeycombs are famous for their elegant design, but now they may have found a new application: quantum computing. To collect knowledge from subatomic particles, quantum computers require carefully designed materials capable of performing necessary, complex functions. However, the metals used, such as ruthenium and iridium, are often rare and expensive, limiting the potential to build new technology.

In an article recently published in Physical Review Materials, researchers from SANKEN at The University of Osaka and collaborating institutions reported the creation of a special thin-film material in which cobalt atoms formed local honeycomb arrangements embedded inside a larger honeycomb matrix. These cobalt honeycomb motifs exhibit strong magnetic interactions, which are important for quantum computing applications.

Kitaev materials, a class of quantum magnetic materials studied for their potential use in quantum information science, have attracted major attention because they may host exotic quantum states known as spin liquids.

In spin liquids, unlike typical liquid matter, the arrangement of spin can stay fluid even when the temperature drops. This is because the needle-like spins constantly flip as they are unable to satisfy all the forces influencing them. One approach to form these liquids involves using a honeycomb-shaped crystal lattice, in which strong interactions between neighboring magnetic ions can be competing intensely.

“Previous work in this area has largely been limited to rare metals like ruthenium and iridium,” says lead author Hao-Bo Li. “We asked whether cobalt, one of the most common transition metals on Earth, could be made to form the same honeycomb structure and display the same intriguing physics.”

The team created their material by adding about 4% cobalt into sodium antimonate (NaSbO₃), a compound that already possesses a layered honeycomb structure. Careful microscopy measurements confirmed that the honeycomb arrangement remained stable without forming unwanted secondary phases.

“What excites us is that these cobalt honeycombs appear to form naturally, without any special coaxing,” explains senior author, Hidekazu Tanaka. “They even produce a clear magnetic signal that matches what theory predicts for this type of structure.”

Magnetic measurements revealed that the compound exhibits a ferromagnetic-like state at temperatures of around 88 K. The theoretical calculations predict that magnetic properties arise because cobalt atoms tend to gather locally inside the material, forming edge-sharing CoO₆ honeycomb motifs.

“Cobalt is relatively cheap, widely available, and already used in semiconductor manufacturing,” remarks Li. “This approach could eventually lead to quantum computing components that are far more practical to produce at scale.”
The research team is now working to apply further engineering techniques to the material and probe its properties in greater detail. With cobalt already embedded in the infrastructure of modern technology, the path from laboratory curiosity to real-world quantum devices may be shorter than expected. This scientific breakthrough potentially paves the way for lower-cost quantum computing materials.
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The article, “Ferromagnetic-like behavior emerging from local CoO₆ honeycomb motifs in Co-doped NaSbO₃ thin films,” was published in Physical Review Materials at DOI: https://doi.org/10.1103/54cx-6r5s

About The University of Osaka
The University of Osaka was founded in 1931 as one of the seven imperial universities of Japan and is now one of Japan's leading comprehensive universities with a broad disciplinary spectrum. This strength is coupled with a singular drive for innovation that extends throughout the scientific process, from fundamental research to the creation of applied technology with positive economic impacts. Its commitment to innovation has been recognized in Japan and around the world. Now, The University of Osaka is leveraging its role as a Designated National University Corporation selected by the Ministry of Education, Culture, Sports, Science and Technology to contribute to innovation for human welfare, sustainable development of society, and social transformation.
Website: https://resou.osaka-u.ac.jp/en