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

The ab-plane optical properties of the high-temperature superconductor Bi2S r2CaCu2O8 are anisotropic in both the normal and the superconducting state. Consistent with the orthorhombic structure, the principal axes lie along t he a and b crystallographic axes, nearly 45 degrees from the Cu-O bond dire ction. In the normal state, analysis of the temperature-dependent optical c onductivity suggests a:scattering rate for the free carriers that shows ab anisotropy in both magnitude and temperature dependence. In;the superconduc ting state, the anisotropy in the oscillator strength of the superfluid res ponse determined from the far-infrared frequency dependence of sigma(2)(ome ga) and from a sum-rule analysis leads to a penetration depth lambda(D) tha t is larger along the b axis than the a axis: (lambda(L)(b)>lambda(L)(a)). [S0163-1829(99)01845-7].