Revolutionary Insights into Magnetism Could Pave the Way for Advanced Quantum Technologies

Physicists at Rice University, led by Zheng Ren and Ming Yi, have made a groundbreaking discovery regarding the magnetic properties of iron-tin (FeSn) thin films, which could significantly impact fields like quantum computing and superconductors. Traditionally, **kagome magnets** — materials with a unique lattice structure — were believed to derive their magnetic properties from itinerant, or mobile, electrons. However, this research has fundamentally challenged that notion by revealing that **localized electrons** are responsible for the magnetism in FeSn. The study, which utilized advanced techniques like *molecular beam epitaxy* and *angle-resolved photoemission spectroscopy*, found that even at high temperatures, the kagome flat bands remained split, a sign of localized electron influence. Moreover, the observation of **selective band renormalization** — a phenomenon where some electron orbitals exhibit stronger interactions than others — adds complexity to understanding how electron behavior affects magnetic properties. This insight was previously noted in iron-based superconductors and now provides a new lens to view kagome magnets. This research not only advances our knowledge of FeSn but also broadens the understanding of materials with similar properties. Insights into the behavior of flat bands and electron correlations hold promise for developing new technologies, such as high-temperature superconductors and quantum computing systems. The collaborative effort, supported by prominent institutions and funding bodies like the U.S. Department of Energy and the Robert A. Welch Foundation, suggests that this discovery will spur further experimental and theoretical investigations into quantum materials.