Change of the vortex lattice symmetry in the vicinity of the macro-to-mesoscopic threshold

In the present work we study the influence of the surface on the vortex structure as a function of the sample size for different temperatures. It is shown that a crossover between a hexagonal lattice, which is characteristic of the macroscopic samples, and a square lattice occurs in the vicinity of a threshold line which delimits the macro and the mesoscopic superconducting regimes, L c ( T ). Such study was carried out by computational simulations where we used the time dependent Ginzburg–Landau equations in the discretized form.