(Nanowerk News) An international team of researchers managed to measure the spin of electrons in matter for the first time – that is, the curvature of the space in which electrons live and move – in “kagome materials”, a new class of quantum materials.
The results obtained – published in Natural Physics (“Flat band separation and strong Berry spin curvature in metal kagome bilayer”) – could revolutionize the way quantum materials are studied in the future, opening the door to new developments in quantum technology, with possible applications in a wide range of technological fields, from renewable energy to biomedical, from electronics to quantum computers.
Success was achieved by the collaboration of international scientists, in which Domenico Di Sante, professor in the Department of Physics and Astronomy “Augusto Righi”, participated for the University of Bologna as part of the Marie Curie BITMAP research project. He was joined by colleagues from CNR-IOM Trieste, Ca’ Foscari University of Venice, University of Milan, University of Würzburg (Germany), University of St. Andrews (UK), Boston College and University of Santa Barbara (USA).
Through advanced experimental techniques, using light produced by the particle accelerator, the Synchrotron, and thanks to modern techniques for modeling the behavior of matter, scientists were able to measure the spin of electrons for the first time, tied to topological concepts.
“If we take two objects such as a soccer ball and a donut, we see that their specific shape dictates different topological properties, for example because a donut has holes, while a ball does not,” explains Domenico Di Sante. “Similarly, the behavior of electrons in materials is affected by certain quantum properties that determine their spin in the matter in which they are found, similar to how the trajectory of light in the universe is modified by the presence of stars, black holes, dark matter, and dark energy, which warps space and time.”
Although the characteristics of these electrons have been known for many years, until now no one has been able to measure these “topological spins” directly. To achieve this, the researchers exploit a particular effect known as “circular dichroism”: a special experimental technique that can only be used with synchrotron sources, which exploits the ability of materials to absorb light differently depending on its polarization.
Scholars have especially focused on “kagome materials”, a class of quantum materials whose name derives from its resemblance to the interweaving of bamboo threads that make up traditional Japanese baskets (called, indeed, “kagome”). These materials are revolutionizing quantum physics, and the results obtained can help us learn more about their special magnetic, topological, and superconducting properties.
“This important result was made possible thanks to the strong synergy between experimental practice and theoretical analysis,” added Di Sante. “The team’s theoretical researchers used state-of-the-art quantum simulation, only possible with the use of powerful supercomputers, and in this way guided their experimental colleagues to specific areas of the material where the circular dichroism effect could be measured.