Recent experiments found superconductivity in nonmagnetic MnB4 with a high critical temperature (Tc) reaching 14 K at 158 GPa. However, ab initio calculations of the electron-phonon coupling predict a Tc below 1 K, suggesting that a conventional mechanism cannot explain this phenomenon. In this Letter, we find that MnB4 is close to an altermagnetic instability in density-functional theory calculations. We propose that the superconductivity is driven by altermagnetic spin fluctuations. To verify the pairing symmetry, we have constructed a two-orbital tight-binding model, where boron states at the Fermi level are integrated out. Using this model, we identify an extended-s symmetry as the leading pairing instability. If confirmed, this will be the first reported case of superconductivity driven by altermagnetic spin fluctuations.
@article{arxiv.2604.21561,
title = {Superconductivity induced by altermagnetic spin fluctuations in high-pressure MnB$_4$},
author = {Danylo Radevych and Mercè Roig and Daniel F. Agterberg and Igor I. Mazin},
journal= {arXiv preprint arXiv:2604.21561},
year = {2026}
}