The recent discovery of superconductivity in unusual materials with nearly flat bands has challenged conventional understanding, prompting researchers to explore new theoretical models, and Zhaoyu Han, Jonah Herzog-Arbeitman from Princeton University, and Qiang Gao now present a particularly insightful approach. They develop exact models demonstrating how superconductivity arises in these flat bands, revealing that a simple attractive interaction between specific orbitals can create a superconducting state, and this is significant because it offers a clear mechanism for understanding the phenomenon. Their work further suggests that even with additional complexities, such as repulsive interactions between electrons, superconductivity can persist if these interactions promote a separation of electron flavours, leaving an underlying attractive force. Importantly, the team finds that the strength of this superconductivity is strongly linked to the material’s quantum geometry and can be optimised by controlling the material’s electron density, potentially paving the way for the design of new, high-temperature superconductors.
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