Recent angle-resolved photoemission spectroscopy (ARPES) and density functional theory plus Hubbard U (DFT+U) studies revealed that a heavy-fermion superconductor CeRh2As2 exhibits van Hove singularities and the Dirac point near the Fermi level EF, which are key signatures of strong-correlation effects and quantum geometry. We have constructed a two-dimensional 12-orbital \textit{Dirac-Anderson} model as an effective model for CeRh2As2. The band structure and Fermi-surface topology of the Dirac-Anderson model agree well with the ARPES data and the DFT+U calculations. We show that the quantum geometry strongly favors magnetic-monopole fluctuations because of the Dirac point at the M point. By solving the linearized \'{E}liashberg equation, we demonstrate that the B1u and B2g representations, spin-triplet states originating from the Dirac point, exhibit the leading superconducting instabilities. By comparing the random-phase approximation and the fluctuation-exchange approximation, we further demonstrate that strong-correlation effects mitigate the influence of quantum geometry. The phase diagram of CeRh2As2 under pressure is discussed in connection with the theoretical results.
@article{arxiv.2510.24289,
title = {Quantum geometric magnetic monopole and two-phase superconductivity in CeRh$_2$As$_2$},
author = {Kosuke Nogaki and Youichi Yanase},
journal= {arXiv preprint arXiv:2510.24289},
year = {2025}
}