Temperature dependence of the upper critical field Hc2 (T) for the
superconducting magnesium diboride, MgB2, is studied in the vicinity of Tc by
using a two-band Ginzburg-Landau (G-L) theory. The temperature dependence of
Hc2 (T) near Tc exhibits a positive curvature. In addition, the calculated
temperature dependence and its higher order derivatives are also shown to be in
a good agreement with the experimental data. In analogy with the multi-band
character of Eliashberg microscopic theory, the positive curvature of Hc2 (T)
is described reasonably by solving the two-band of G-L theory.Comment: 14 pages, 2 figures, submitted to SUST November 200