Publication
Physical Review Letters
Paper
Infrared evidence for gap anisotropy in YBa2Cu3O7
Abstract
Infrared reflectivity measurements of crystalline YBa2Cu3O7 (Tc92 K) are performed with the electric field both parallel and perpendicular to the Cu-O planes. We find evidence for an unusually large in-plane energy gap (8kTc), while a much smaller energy scale (3kTc) is obtained with the field perpendicular to the planes suggesting substantial gap anisotropy. Temperature-dependent measurements near Tc demonstrate a clear relationship between the development of the 8kTc feature and the superconducting transition. © 1989 The American Physical Society.