Dielectric constants from ${10}^2$ to ${10}^6$ are found in room-temperature, ceramic, nonmetallic ${\mathrm{YBa}}_2$${\mathrm{Cu}}_3$${\mathrm{O}}_{6+\mathrm{\delta }}$ (δ∼0–0.4). The frequency, temperature, and electric-field dependencies of the dielectric response, as well as the quasistatic current-voltage behavior of this material, are reported. We show that the high polarizability is tied to a short (≤100 Å) length scale, persists to microwave frequencies, and is accompanied by a strong electric-field dependence.

• Received 6 December 1991

DOI:https://doi.org/10.1103/PhysRevB.45.10639