Anisotropy in the ab-plane optical properties of Bi2Sr2CaCu2O8 single-domain crystals

The ab-plane optical properties of the high-temperature superconductor Bi2Sr2CaCu2O8 are anisotropic in both the normal and the superconducting state. Consistent with the orthorhombic structure, the principal axes lie along the a and b crystallographic axes, nearly 45° from the Cu-O bond direction. In the normal state, analysis of the temperature-dependent optical conductivity suggests a scattering rate for the free carriers that shows ab anisotropy in both magnitude and temperature dependence. In the superconducting state, the anisotropy in the oscillator strength of the superfluid response determined from the far-infrared frequency dependence of s2(v) and from a sum-rule analysis leads to a penetration depth lD that is larger along the b axis than the a axis: (lL .lL ). @S0163-1829~99!01845-7#