Magnetoplasma Cyclotron Absorption in PbSe

Measurements have been made of the derivative of the microwave surface absorption of $p$-type and $n$-type PbSe as a function of static magnetic field H at 70 GHz and 4.2°K. H was parallel to the sample surface (Azbel-Kaner geometry) which was a (100) plane that formed the central section of the bottom wall of a cylindrical cavity resonant in the T${\mathrm{E}}_{113}$ mode. The microwave electric field E was set both parallel and perpendicular to H. Experimental curves obtained with H aligned along the [001] axis and the [011] axis, with the ordinary mode (E∥H) and the extraordinary mode ($\mathbf{E}\perp \mathbf{H}$) of propagation excited independently, show good agreement with curves calculated for a high-density plasma under classical skin-effect conditions, with the assumption of an $〈111〉$ ellipsoid of revolution model for both the valence- and conduction-band extrema, and an appropriate isotropic relaxation time. The main structure in the curves is attributable to either hybrid or tilted-orbit resonances and to dielectric anomalies, but not to Azbel-Kaner resonance. The values deduced for the transverse effective mass $m_t$ and for the anistropy, $K=\frac{m_l}{m_t}$, for the $p$-type specimen which had a carrier concentration of 1.1 × ${10}^{18}$ ${\mathrm{cm}}^{-3\mathrm{}}$, were $m_t=(0.0465\mathrm{}\pm 0.002)m_0$ and $K=1.8\mathrm{}\pm 0.2$, and for the $n$-type specimen ($n=2.9\mathrm{}\times {10}^{17}$ ${\mathrm{cm}}^{-3\mathrm{}}$) were $m_t=(0.041\mathrm{}\pm 0.002)m_0$ and $K=1.67\mathrm{}\pm 0.2$. Weak structure was also observed at low magnetic fields, which may be due to nonlocal effects such as subharmonic Azbel-Kaner resonance.