Superconducting Meron Phase in Locally Noncentrosymmetric Superconductors

Area of Science:

• Condensed Matter Physics
• Superconductivity Theory

Background:

• Superconducting parity transitions involve changes in the parity of the superconducting state.
• Vortex degrees of freedom are crucial in understanding complex superconducting phenomena.
• Layered superconductors with non-centrosymmetric structures exhibit unique electronic properties.

Purpose of the Study:

• To extend the theory of superconducting parity transitions by incorporating the vortex degree of freedom.
• To investigate the influence of magnetic fields on parity transitions in layered superconductors.
• To predict novel superconducting states and their properties.

Main Methods:

• Employing the bilayer Rashba model for locally non-centrosymmetric layered superconductors.
• Deriving the Ginzburg-Landau free energy functional.
• Analyzing the H-T phase diagram and predicting spin textures.

Main Results:

• The theory reveals a parity transition from even- to odd-parity superconducting states with increasing magnetic field under vortex states.
• The H-T phase diagram of CeRh_{2}As_{2} is quantitatively reproduced.
• A novel superconducting state featuring a meron (half-skyrmion) lattice pseudospin texture is predicted.

Conclusions:

• The inclusion of vortex degrees of freedom is essential for a complete understanding of superconducting parity transitions.
• The proposed model accurately describes experimental observations in materials like CeRh_{2}As_{2}.
• The prediction of a meron lattice state opens new avenues for exploring exotic superconducting phases.