Large dielectric constants and massive carriers inLa2CuO4

We report measurements of the conductivity and dielectric constant as a function of frequency and temperature on samples of ${\mathrm{La}}_2$ ${\mathrm{CuO}}_4$ from dc to 100 GHz. An analysis of the frequency dependence of the complex conductivity indicates that the high-frequency dielectric constant is large (≃50) and weakly temperature dependent. The dc charge carriers are massive (1100${\mathrm{m}}_{\mathrm{e}}$), weakly damped, and partially pinned.