Magnon-mediated superconductivity at the interface between a ferromagnetic insulator and a topological crystalline insulator with wallpaper fermions
Phys. Rev. B 112, 035303 – Published 14 July, 2025
DOI: https://doi.org/10.1103/sknv-r7wq
Abstract
We study two-dimensional superconductivity mediated by magnetic fluctuations at the interface between a ferromagnetic insulator and the nonsymmorphic topological crystalline insulator with a fourfold-degenerate Dirac point wallpaper fermion. We demonstrate that BCS pairing with zero center-of-mass momentum induces chiral -wave superconductivity, and the Amperean pairing with center-of-mass momentum can give rise to a parity-mixed superconducting state. We find that the Amperean pairing exhibits a mixture of -wave and -wave components due to the multiband nature of the wallpaper fermion and the easy-axis anisotropy of the ferromagnetic insulator. Additionally, we find that the stability of the superconducting state with BCS and the Amperean pairing is governed by the easy-axis anisotropy.