  Our study sample is a superconducting bi-dimensional octagon with different
boundary conditions immersed in a magnetic external field H. The boundary
conditions are simulated by considering different values of the deGennes
extrapolation length b on different surfaces of the sample. Our investigation
was carried out by solving the two-band time dependent Ginzburg-Landau
equations (TB-TDGL). We analyzed the superconducting electron density and the
magnetization curves as functions of H and temperature T in zero field cooling
and in zero field cooling processes for different values of b and size of the
sample. We found a strong dependence of the critical fields on b and size of
the sample.

Superconductivity