Fractional vortex lattice structures in spin triplet superconductors

Abstract

Motivated by recent interest in spin triplet superconductors, we investigate the vortex lattice structures for this class of unconventional superconductors. We discuss how the order parameter symmetry can give rise to U(1)$\times$U(1) symmetry in same sense as in spinor condensates, making half-quantum vortices (HQV) topologically stable. We then calculate the vortex lattice structure of HQV's, with particular attention on the roles of the crystalline lattice, the Zeeman coupling, and Meissner screening, all absent in spinor condensates. Finally, we consider how spin-orbit coupling leads to a breakdown of the U(1)$\times$U(1) symmetry in free energy and whether the HQV lattice survives this symmetry breaking. As examples, we examine simpler spin-triplet models proposed in the context of NaxCoO2$\cdot$yH2O and Bechgaard salts, as well as the better known and more complex model for Sr2RuO4.

13 pages, 6 figures. The version published in New Journal of Physics focus issue on 'Superconductors with Exotic Symmetry' with added references

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Cited by in corpus (12)

• Skyrmionic state and stable half-quantum vortices in chiral p-wave superconductors
• Vortical versus skyrmionic states in mesoscopic \emph{p}-wave superconductors
• Superfluid drag in the two-component Bose-Hubbard model
• Skyrmions induced by dissipationless drag in U(1)xU(1) superconductors
• Quantum Gutzwiller approach for the two-component Bose-Hubbard model
• Spin-orbit Coupling and Multiple Phases in Spin-triplet Superconductor Sr${}_2$RuO${}_4$
• Anomalous vortex dynamics in spin-triplet superconductor UTe${}_2$
• Spin-Triplet Pairing State of Sr2RuO4 in the c-Axis Magnetic Field
• Entropy driven formation of a half-quantum vortex lattice
• Vortex liquid phase in the p-wave ferromagnetic superconductor UCoGe
• Integer and fractionalized vortex lattices and off-diagonal long-range order
• Effect of Dipole Energy on Half-Quantum Vortex in Superfluid Polar Phase