Fundamental properties of a vortex in a d-wave superconductor

TL;DR

This paper investigates the unique four-fold symmetric vortex core structure in d-wave superconductors using quasi-classical theory, explaining experimental flux line lattice orientations in cuprates.

Contribution

It provides a theoretical analysis of vortex properties in d-wave superconductors beyond Ginzburg-Landau, highlighting symmetry breaking and quasiparticle effects.

Findings

Vortex core exhibits four-fold symmetry in d-wave superconductors.

Current and magnetic field distributions break circular symmetry.

The theory explains observed flux line lattice orientations in cuprates.

Abstract

The vortex core structure in a d-wave superconductor is analyzed on the basis of the quasi-classical Eilenberger theory beyond the Ginzburg-Landau framework. The current and magnetic field distributions around an isolated vortex break circular symmetry seen in s-wave pairing and show four-fold symmetry, reflecting the internal degrees of freedom in d-wave pairing, {\it i.e.} $\hat k_x^2-\hat k_y^2$ in reciprocal space through the low lying quasi-particle excitations. The peculiar orientation of the flux line lattice observed recently in a cuprate is argued in light of the present theory.