Temperature dependence of transmittance and effective surface resistance of MgB2 film

Using the Kubo formula approach and Green's function method, the temperature dependence of the transmittance and effective surface resistance of high quality MgB2 film are calculated in the framework of the two-band model. For large interval of temperatures below TC our results are in agreement with experimental data. We show a single-gap model based on BCS theory, which is insufficient to understand such quantities, but a two-band model with different symmetries can describes the experimental data rather well. In the two-gap model we consider that the transmittance and effective surface resistance are a weighted sum of the contributions from σ and π bonds and hybridization between them is negligible.