A breakthrough made by physicists is paving the way for a new insight into magnetism and electronic interactions in advanced materials, which could significantly transform areas like quantum computing and high-temperature superconductors.
A team of physicists from Rice University, led by Zheng Ren and Ming Yi, has made a significant discovery regarding iron-tin (FeSn) thin films. This research is redefining our understanding of kagome magnets—materials named after a traditional weaving pattern and characterized by a unique lattice structure that can produce extraordinary magnetic and electronic behaviors, attributed to the quantum destructive interference of electron wave functions.
The results, which were published in Nature Communications on October 30, indicate that the magnetic characteristics of FeSn originate from localized electrons, contrary to the previously held belief that mobile electrons were responsible. This revelation challenges current theories related to magnetism in kagome metals, suggesting that localized electrons play a critical role rather than itinerant electrons. This new perspective on magnetism could pave the way for developing new materials with specialized characteristics for advanced technological applications like quantum computing and superconductors.
“This research is anticipated to encourage additional experimental and theoretical exploration into the emerging attributes of quantum materials, enriching our comprehension of these complex materials and their practical applications,” stated Yi, who is an associate professor of physics and astronomy as well as a Rice Academy Senior Fellow.
Employing an innovative approach that merges molecular beam epitaxy with angle-resolved photoemission spectroscopy, the researchers successfully produced high-quality FeSn thin films and scrutinized their electronic structure. They discovered that even at higher temperatures, the kagome flat bands remained split, signaling that localized electrons are responsible for the magnetism observed in this material. This electron correlation brings an added layer of complexity in understanding how electron behavior affects magnetic properties within kagome magnets.
The research also identified that certain electron orbitals exhibited stronger interactions than others, a phenomenon named selective band renormalization, which has been previously noted in iron-based superconductors. This new perspective sheds light on how electron interactions can influence the behavior of kagome magnets.
“Our investigation emphasizes the intricate relationship between magnetism and electron correlations in kagome magnets, indicating that these effects significantly contribute to their overall properties,” expressed Ren, a Rice Academy Junior Fellow.
In addition to enhancing the understanding of FeSn, this research holds potential implications for materials with similar traits. Insights into flat bands and electron correlations could play a key role in the advancement of new technologies, such as high-temperature superconductors and topological quantum computation, where the interaction of magnetism and topological flat bands creates quantum states suitable for use as quantum logic gates.
The Rice research team included postdoctoral associates and graduate students from the Department of Physics and Astronomy: Jianwei Huang, Ananya Biswas, Yichen Zhang, Yaofeng Xie, Ziqin Yue, Lei Chen, Fang Xie, Kevin Allen, Han Wu, and Qirui Ren; Junichiro Kono, the Karl F. Hasselmann Professor of Engineering and head of the Smalley-Curl Institute; Emilia Morosan, a professor of physics and astronomy as well as chemistry and materials science and nanoengineering; Qimiao Si, the Harry C. and Olga K. Wiess Professor of Physics and Astronomy; and Pengcheng Dai, the Sam and Helen Worden Professor of Physics and Astronomy.
International collaborators included Hengxin Tan and Binghai Yan from the Department of Condensed Matter Physics at the Weizmann Institute of Science; Aki Pulkkinen and Ján Minár from the New Technologies Research Center, University of West Bohemia; Anil Rajapitamahuni, Asish K. Kundu, and Elio Vescovo from the National Synchrotron Light Source II, Brookhaven National Lab; and Jian-Xin Zhu from the Theoretical Division and Center for Integrated Nanotechnologies at Los Alamos National Laboratory.
This research was funded by several organizations, including the U.S. Department of Energy, the Robert A. Welch Foundation, the Gordon and Betty Moore Foundation’s EPiQS Initiative, the Rice Academy of Fellows, the Air Force Office of Scientific Research, and the Vannevar Bush Faculty Fellowship.
