Anisotropic properties of ${\mathrm{La}}_{8\mathrm{-}\mathit{x}}$${\mathrm{Sr}}_{\mathit{x}}$${\mathrm{Cu}}_8$${\mathrm{O}}_{20\mathrm{-}\mathrm{\delta }}$ epitaxial thin films

${\mathrm{La}}_{8\mathrm{-}\mathit{x}}$ ${\mathrm{Sr}}_{\mathit{x}}$ ${\mathrm{Cu}}_8$ ${\mathrm{O}}_{20\mathrm{-}\mathrm{\delta }}$ thin films are epitaxially grown on ${\mathrm{SrTiO}}_3$ single-crystal substrates by rf magnetron sputtering. They exhibit anisotropic electrical and optical properties in directions from parallel to perpendicular to the c axis, but the degree of anisotropy is smaller than that found in the usual high-${\mathit{T}}_{\mathit{c}}$ superconductors. The resistivity in the [001] direction is metallic and that in the [100] direction exhibits a broad peak at about 180 K. The anisotropic behavior can be explained by assuming that this matter has a quasi-one-dimensional electronic structure. Furthermore, the Hall coefficients are negative and decrease rapidly with decreasing temperature. The plasma frequency ${\mathrm{\omega }}_{\mathit{p}}$ is about 1.3 eV and this value is near that of Ba(Pb,Bi)${\mathrm{O}}_3$.