Abstract
We report observation of circular dichroism in reflection from various cuprate superconducting materials, including YBa2Cu2O7-x films, an etched YBa2Cu3O7 crystal, and a Bi2Sr2CaCu2O8 crystal. This signal develops as T is lowered below 200 K and exhibits little change near Tc. The exact onset temperatures differ for the various materials. © 1990 The American Physical Society.