Anisotropy of the upper critical field in MgB$_{2}$: the two-band Ginzburg–Landau theory

The temperature dependence of the anisotropy parameter of upper critical field $\gamma _{H_{c2}}(T)={H_{c2}^{\parallel }(T)}/{H_{c2}^{\perp }(T)}$ is calculated using two-band Ginzburg–Landau theory for layered superconductors. It is shown that, with decreasing temperature anisotropy parameter $\gamma (T)$ is increased. Result of calculations are in agreement with experimental data for single crystals of MgB$_{2}$ and with other calculations.