Spin-valley locking and pure spin-triplet superconductivity in noncollinear antiferromagnets proximitized to conventional superconductors

Unconventional antiferromagnets with spin-split bands, such as noncollinear magnets and the recently discovered altermagnets, serve as new constituents for exploring unconventional superconductivity. Here, we reveal a distinct even-parity type of spin-valley locking in noncollinear antiferromagnets and exploit this texture to achieve pure spin-triplet superconductivity. Using chiral antiferromagnetic kagome lattices (e.g., Mn 3 Ge and Mn 3 Ga) coupled to conventional s -wave superconductors as prototypical examples, we demonstrate that the valley-locked spin texture strongly favors spin-triplet pairing via superconducting proximity effect while rapidly suppressing spin-singlet pairing in the antiferromagnets away from the interfaces over a broad energy range. Crucially, such a spin-triplet superconducting state is established without invoking the prevailing mechanism of spin-orbit coupling or net magnetization. Furthermore, the spin-triplet supercurrent is resilient to both in-plane and out-of-plane Zeeman splitting fields and spin canting in the antiferromagnet, serving as a compelling experimental signature of the triplet pairing and spin-valley-locked texture.