Spin triplet pairing by suppressing altermagnetism

Abstract

The interplay between unconventional superconductivity and altermagnetic order has attracted much attention. In particular, whether spin-triplet superconductivity can be achieved by suppressing altermagnetism remains an open issue. We investigate this issue using a minimal single-orbital Hubbard model on a square lattice with a vacancy superstructure, in which both conventional antiferromagnetic and altermagnetic orders can emerge on an equal footing. We illustrate the existence of a metallic normal phase with altermagnetism even at half-filling due to geometric frustration and Coulomb interaction. Suppressing the altermagnetic long-range order using charge doping can lead to both conventional antiferromagnetic and altermagnetic spin fluctuations. Spin-singlet pairing is always favored when conventional antiferromagnetic spin fluctuations dominate. However, when altermagnetic spin fluctuations dominate, spin-triplet pairing will be induced. Implications of our results for possible material candidates are also briefly discussed.

v2: Updated to match the published journal version, Phys. Rev. B 114, L080509 (2026). Minor revisions to text and figures