Triplet Pairing Mechanisms from Hund?s-Kondo Models: Applications to UTe2 and CeRh2As2

Observing that several U and Ce based candidate triplet superconductors share a common structural motif, with pairs of magnetic atoms separated by an inversion center, we hypothesize a triplet pairing mechanism based on an interplay of Hund's and Kondo interactions that is unique to this structure. In the presence of Hund's interactions, valence fluctuations generate a triplet superexchange between electrons and local moments. The offset from the center of symmetry allows spin-triplet pairs formed by the resulting Kondo effect to delocalize onto the Fermi surface, precipitating superconductivity. We demonstrate this mechanism within a minimal two-channel Kondo lattice model and present support for this pairing mechanism from existing experiments.

Automated summary

Observing a common structural motif in several U and Ce based candidate triplet superconductors, where pairs of magnetic atoms are separated by an inversion center, we propose a unique triplet pairing mechanism based on an interplay of Hund's and Kondo interactions. Hund's interactions generate valence fluctuations, leading to a triplet superexchange between electrons and local moments. The resulting Kondo effect allows spin-triplet pairs to delocalize onto the Fermi surface, triggering superconductivity. We demonstrate this mechanism using a minimal two-channel Kondo lattice model and provide support from existing experiments.