Possible Spin Triplet Pairing due to Altermagnetic Spin Fluctuation

Abstract: The interplay between unconventional superconductivity and altermagnetic order has attracted much attentions. 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 vacancy superstructure, in which both conventional antiferromagnetic and altermagnetic order can emerge on equal footing. We illustrate the existence of a metallic normal phase with altermagnetism even at half-filling due to the geometric frustration and Coulomb interaction. Suppressing the altermagnetic long-range order using charge doping can lead to both conventional antiferromagnetic and altermagnetic spin fluctuation. The spin-singlet pairing is always favored when the conventional antiferromagnetic spin fluctuation dominates. However, when the altermagnetic spin fluctuation dominates, spin-triplet pairing may be induced. Implications of our results in possible material candidates are also briefly discussed.