INVESTIGATION ON THE GROUND-STATES OF A MODEL THIN-FILM SUPERCONDUCTOR ON A SPHERE

We consider the problem of finding the ground state of a model type-II superconductor on the two-dimensional surface of a sphere, penetrated by N vortices. Numerical work shows the ground states to consist of a triangular network of the vortices with twelve five-coordinated centr es. Values of N are found with particularly low-energy ground states, due to structures of high symmetry. The large-N limit is treated withi n elasticity theory to compare with the triangular vortex lattice that forms the ground state on an infinite flat plane. Together with numer ical work this demonstrates that the thermodynamic limit N --> infinit y of the spherical system remains different from the fat plane due to the presence of twelve disclination defects.