The vortex core structure in a d-wave superconductor is analyzed by solving the quasi-classical Eilenberger equation self-consistently. The pair function, current and magnetic field distributions around an isolated vortex are found to break circular symmetry and show four-fold symmetry, reflecting the internal degrees of freedom in d-wave pairing.
Recently, Keimer et al. [1] reported a small-angle neutron scattering experiment on YBa2Cu30 7 to observe the flux-line lattice (FLL) in the magnetic field region 0.5 T _<_< H < 5 T and found that the vortices form an oblique lattice with two equal lattice constants and an angle of 73 Β° between the two primitive vectors. The FLL is oriented such that the nearest-neighbor direction of the vortices makes an angle of 45 Β° with the a-axis (or b-axis) of the underlying orthorhombic crystal lattice when the field H is applied to the c-axis. This result seems to be difficult to understand within the framework of the Ginzburg-Landau theory (GL). In order to stabilize such an orientation of the FLL, one of the primitive vectors must be aligned, making an angle of 9 Β° with the a-axis. A recent STM experiment under fields by Maggio-Aprile et al. [2] also exhibits a non-trivial vortex structure in high-T c cuprates.
Here we examine the vortex core structure of d-wave superconductivity. This study underlies a