On relaxation of exciton excitations in high-Tc superconductors

Based on the assumption that the optical d d-transitions in high-Tc superconducting compounds are related to the excitation of bound states of electrons and holes-excitons, the relaxation of the latter on free carriers is considered. It is that the observed sharp temperature dependence of absorption (transmission) intensity due to exciton excitation (initially 3 d9→3 d9 transitions Cu2+ ions) can be accounted for by a superconducting transition in the two-dimensional free carrier subsystem