The presence of the superconducting energy gap, 2〉, in YBa2Cu3O6.74 has been observed directly at 45 ±5 cm-1 and at 1.6 K by far-infrared absorption measurements in small particles embedded randomly in a polyethylene film. This result indicates that the gap has the minimum of 2〉min≃0.7 kTc, and thus the gap is finite along any direction in the crystal. Transverse effective charges associated with polar optical phonons at 144, 280, and 315 cm-1 increase by a factor of 4 ~ 5 upon a decrease in the temperature from 295 K to 1.6 K, suggesting the presence of an anomalous electron-phonon coupling in this material.
ASJC Scopus subject areas
- Physics and Astronomy(all)