MgB₂ holds the record critical temperature for a conventional, phonon-mediated superconductor, about 39 K. An international team has revisited it with compact analytic models of its electrons, phonons and electron–phonon coupling, built from minimal first-principles input.

They show that the boron bonding produces an electronic structure best described as a bond-centred kagome lattice, with pronounced quantum-geometric effects. Calculations indicate that light electron doping should raise the critical temperature in the clean limit, and that this enhancement is overwhelmingly quantum-geometric in origin, suggesting quantum geometry can shape doping trends even in conventional superconductors. From QMAT, Päivi Törmä's Quantum Dynamics group at Aalto University took part, with Kaja Hiorth and Junze Deng; partners include DIPC, Princeton and Rice University.

The preprint has not yet been peer reviewed.

Figure: Jiang et al., arXiv:2607.19458 (2026), CC BY 4.0