A kagome crystal features two-dimensional atomic layers whose structure resembles a traditional Japanese basket weave called kagome. For several decades, the kagome crystals that attracted the most attention were insulating magnets. The geometric frustration inherent in their kagome structure could, it was hoped, engender a much-sought exotic state known as a quantum spin liquid. By contrast, the metallic side of the kagome family was more of a theoretical curiosity. That status changed in 2019 with the discovery of exotic electronic behavior—Dirac fermions and flat bands—in the kagome metal FeSn [1]. A bigger surprise followed a year later when superconductivity was observed in the kagome metal cesium vanadium antimonide (CsV3Sb5, or CVS for short) [2]. Now a team led by Jian Wang of Peking University has reported that a kagome crystal displays a unique phenomenon for conventional superconductors: the emergence of quasiparticles with an electric charge 4 and 6 times that of an isolated electron [3]. The finding challenges the expectation that electron binding forces grow substantially weaker with the number of involved electrons, which could pave the way to uncovering new forms of superconductivity.

To read more, click here.