Correlation of the Infrared Anomaly and Superconductivity in YBa₂(Cu_1−xCo_x)₃O_7−δ

Abstract

For YBa₂Cu₃O_7−δ oxides sintered at various temperatures, the infrared absorption mode of in-plan Cu(2)–O(2, 3) stretching motions shows the anomalous behavior to disappear for superconducting samples although it is allowed by the selection rule. The correlation between the infrared anomaly and superconductivity has been confirmed systematically for YBa₂(Cu_1−xCo_x)₃O_7−δ system in the Co concentration region of 0≤x≤0.3 for samples quenched from sintering temperatures of 400, 500, 600, 700 and 800°C.