Boson–fermion mixture model of superconductivity and pseudogap phenomena

A concept describing the origin of the pseudogap phase of high- T c-superconducting cuprates is discussed. Based on the idea about electron–composite boson mixture, existing below some value T p in cuprates, first, an analytical expression for T p is obtained. It is shown that T p depends on interaction parameter responsible for two electron–composite boson transformation, as well on the boson formation energy. Second, the composite boson condensation temperature T c, determined as a one below which the density of condensed bosons just ceases to be zero, is found. The reason why the behaviors of T p and T c in dependence on the interaction parameter may be so different is addressed.