OPTICAL-RESPONSE TO SUPERCONDUCTING TRANS ITION - ALTERNATIVE CRITERIA FOR INFRARED AND VISIBLE FREQUENCY RANGES

Comparison optical measurements of temperature behavior of transmissio n of superconducting YBa2Cu3O6-x films are performed in visible and in frared light fields. We manage to distinguish two electronic structura l ortho-states (high- and low temperature phase) which define the alte rnative temperature behaviors of visible and infra-red transmission an d the sensitivity to T-c. The experimental data suggest that there are two different mechanisms of pairing in the HP and LP phases which are responsible for the formation of a two-component superconductivity co ndensate in YBa2Cu3O6+x.