Vakula V. Antiferromagnetic correlations and stripe state in YBCO as seen from optical absorption data

Processes of metallization and antiferromagnetic ordering in copper oxides. To study features of competition and coexistence of antiferromagnetic correlations and band carriers in YBCO, including the question of stripe ordering in this material. The investigation method is low-temperature optical absorption spectroscopy of thin films at interband transitions. The new exciton-two-magnon resonance is found in the metallic phase of YBCO. The formation of stripe ordering in the normal phase and its persistence in the superconducting phase is shown. Evidence of temperature compatibility of the stripe ordering and the pseudogap state is obtained. The question concerning changes in the level of oxygen-copper hybridization upon doping level and temperature variation is studied. The field of practical use is resolving some fundamental problems of the physics of strongly correlated electronic systems, development of superconducting film opto-electronic devices