Spin Currents and Spontaneous Magnetization at Twin Boundaries of Noncentrosymmetric Superconductors

Abstract

Twin boundaries are generic crystalline defects in noncentrosymmetric crystal structures. We study theoretically twin boundaries in time-reversal symmetric noncentrosymmetric superconductors that admit parity-mixed Cooper pairing. Twin boundaries support spin currents as a consequence of this parity mixing. If the singlet and triplet components of the superconducting order parameter are of comparable magnitude, the superconducting state breaks spontaneously the bulk time-reversal symmetry locally near the twin boundary. By self-consistently evaluating the Bogoliubov-de-Gennes equations and the gap functions we find two distinct phases: First, time-reversal symmetry breaking enhances the spin currents but does not lead to chiral supercurrents. A secondary phase transition then triggers a spin magnetization and an orbital supercurrent near the twin boundary.

4 pages, 3 figures

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• Signatures of the Helical Phase in the Critical Fields at Twin Boundaries of Non-Centrosymmetric Superconductors
• Effects of spin orbit coupling in superconducting proximity devices -- application to $\mathrm{CoS}{\mathrm{i}}_2/TiS{\mathrm{i}}_2$ heterostructures
• Magnetically-textured superconductivity in elemental Rhenium
• Ginzburg-Landau description of twin boundaries in noncentrosymmetric superconductors
• Spin Current in Junctions composed of Multi-band Superconductors with a Spin-density Wave
• Singlet-triplet mixing in the order parameter of the noncentrosymmetric superconductor Ru${}_7$B${}_3$
• Interface currents and magnetization in singlet-triplet superconducting heterostructures: Role of chiral and helical domains
• Kinetic stabilization of 1D surface states near twin boundaries in noncentrosymmetric BiPd
• Adherence of the rotating vortex lattice in the noncentrosymmetric superconductor Ru${}_7$B${}_3$ to the London model