Half-quantum vortices on c-axis domain walls in chiral p-wave superconductors

Abstract

Chiral superconductors are two-fold degenerate and domains of opposite chirality can form, separated by domain walls. There are indications of such domain formation in the quasi two-dimensional putative chiral p-wave superconductor Sr _2 RuO _4 , yet no experiment has explicitly resolved individual domains in this material. In this work, c -axis domain walls lying parallel to the layers in chiral p-wave superconductors are explored from a theoretical point of view. First, using both a phenomenological Ginzburg–Landau and a quasiclassical Bogoliubov-de Gennes approach, a consistent qualitative description of the domain wall structure is obtained. While these domains are decoupled in the isotropic limit, there is a finite coupling in anisotropic systems and the domain wall can be treated as an effective Josephson junction. In the second part, the formation and structure of half-quantum vortices on such c -axis domain walls are discussed.

Keywords

• unconventional superconductivity
• chiral p-wave
• domain walls
• half-quantum vortices
• effective Josephson junctions
• sine-Gordon model