Local and Nonlocal Magnetoplasma Effects inn-Type Lead Telluride

Measurements of the derivative of the microwave absorption coefficient as a function of static magnetic field H have been carried out in high-mobility (1.0×{}10⁶ cm²/V sec) n-type lead telluride at 70 GHz and 4.2^∘{}K. The measurements were taken in the Voigt (q₀⊥H, where q0 is the incident radiation wave vector) and Faraday (q₀∥H) configurations, as well as in intermediate geometries, where a mixed Voigt-Faraday situation applied. The sample surface, a {110} plane, was fixed perpendicular to q0, and H was rotated in a {100} plane which contained q0. The data were analyzed using well-known local theory and a simplified nonlocal theory for the Azbel-Kaner and Doppler-shifted cyclotron resonances. The observed local magneto-plasma effects agreed with those predicted from the $〈111〉$-ellipsoid model and included the hybrid resonance which has not been previously reported in lead telluride. The values deduced for the transverse mass mₜ and the mass ratio K=mₗmₜ were mₜm₀=0.043±0.04 and K=9.7±1.4 at a carrier concentration of 8.1×{}10¹⁷ cm^-3. Two weak, low-field resonances were identified as the first and second Azbel-Kaner subharmonics of a tilted-orbit cyclotron resonance. The values of the magnetic field at which the resonances and dielectric anomalies were observed in the Faraday geometry were shifted 4-19% relative to the corresponding values in the Voigt geometry, and some of these shifts agreed with the predictions of the simple Doppler-shift theory. Analysis of the Voigt dielectric-anomaly data gave a value of 10⁴ for the static part of the lattice dielectric constant. A similar value has been obtained in microwave-helicon experiments, while other methods of determination have given values near 400.