2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/18754Temperature dependence of the lower critical field Hc1 (T) for the superconducting magnesium diboride, MgB2, is studied in the vicinity of Tc by using a two-band Ginzburg-Landau (G-L) theory. Theoretically calculated Hc1 (T) near Tc exhibits a negative curvature. The results are shown to be in a good agreement with the experimental data. In addition, two-band G-L theory calculations give a temperature dependence of the Ginzburg-Landau parameter, which varies little with temperature as in a similar manner of the microscopic single-band BSC theory.14 pages, 2 figuresSuperconductivitytext