Peculiarity of plasma reflection and HTSC electronic structure

Main perculiarities of plasma reflection, observed in superconducting phase of HTSC-materials have been analyzed. Their explanation on the basis of available models of HTSC electronic structure is given. It is shown that some of the mentioned peculiarities (absence of plasma frequency dependence on doping degree or oxygen stoichiometry) can be explaned only in the framework of traditional band concepts. Conflicts of the band model with the experiment are resolved successfully if it is proposed that there is a pseudogap of state density, occurring for example due to antiferromagnetic fluctuations