Quantum Geometry and Matter Group

This work shows that anisotropic Josephson coupling between spin-triplet superconducting grains can frustrate both condensate phases and relative d-vector orientations, producing emergent geometric phases, spontaneous Josephson currents, and nonintegral flux trapping. The authors identify a three-grain-ring example in which sufficiently strong antisymmetric Josephson coupling drives time-reversal-symmetry breaking, chiral d-vector textures, and spontaneous half-flux-quantum trapping. Its importance lies in establishing the internal spin structure of Cooper pairs as a distinct mechanism for frustration, beyond fixed tunneling phase shifts or orbital pairing symmetry. The work therefore offers a route to engineer frustrated Josephson networks through the interplay of magnetic textures and triplet pairing order, with relevance to polycrystalline and single-crystal superconducting systems.