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×${10}^6$ ${\mathrm{cm}}^2$/V sec) $n$-type lead telluride at 70 GHz and 4.2°K. The measurements were taken in the Voigt (${\mathbf{q}}_0\perp \mathbf{H}$, where q0 is the incident radiation wave vector) and Faraday (${\mathbf{q}}_0\parallel \mathbf{H}$) 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 $m_t$ and the mass ratio $K=\frac{m_l}{m_t}$ were $\frac{m_t}{m_0}=0.043\mathrm{}\pm 0.04$ and $K=9.7\mathrm{}\pm 1.4$ at a carrier concentration of 8.1×${10}^{17}$ ${\mathrm{cm}}^{-3\mathrm{}}$. 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 ${10}^4$ 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.