Vortex state in a superconducting mesoscopic irregular octagon

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 de Gennes extrapolation length b on different surfaces of the sample. Our investigation was carried out by solving the time-dependent Ginzburg-Landau equations. We analyzed the superconducting electron density and the magnetization curves as functions of H and temperature T in 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.