Infrared anisotropy ofLa1.85Sr0.15CuO4−y

By calculating the infrared reflectance $R\left(\omega \right)$ for a collection of randomly oriented crystallites, we fit the reflectance of polycrystalline ${\mathrm{La}}_{1.85}{\mathrm{Sr}}_{0.15}\mathrm{Cu}{\mathrm{O}}_{4-y}$. From this calculation, the normal state of ${\mathrm{La}}_{1.85}{\mathrm{Sr}}_{0.15}\mathrm{Cu}{\mathrm{O}}_{4-y}$ is found to be metallic in the Cu-O planes and nonmetallic out-of-plane. The deconvolution of $R\left(\omega \right)$ into $R_{\parallel }$ and $R_{\perp }$ allows the anisotropy of the system to be examined and provides a method by which infrared measurements of polycrystalline materials can be interpreted.