Submillimeter Cyclotron Resonance and Related Phenomena in HgTe

We present the results of far-infrared magnetotransmission experiments on mercury telluride. The experiments are performed on $n$-type samples in theFaraday and Voigt geometries in the wavelength range from 2 mm to 100 μm at 4.2 K and in magnetic fields up to 58 kG. Both intraband transitions in the ${\Gamma }_8$ conduction band, such as cyclotron resonance, and interband ${\Gamma }_8\to {\Gamma }_8$ transitions are observed: To analyze the position of the plasma-cylotron-resonance line observed in the Voigt geometry, we discuss the frequency and magnetic field dependence of all the contributions to the dielectric function including that which arises from the interband ${\Gamma }_8\to {\Gamma }_8$ transitions. The Luttinger parameters ${\gamma }_1$, $\overline{\gamma }$, and $\kappa$ describing the quantum levels in the ${\Gamma }_8$ bands near the degeneracy point at $\overrightarrow{\mathrm{k}}=0\mathrm{}$ are determined. Absorption lines due to transitions between a discrete acceptor state degenerate with the conduction band and the quantum levels of the conduction band are observed. The activation energy of this acceptor state is found to be $E_A=0.7\mathrm{}\pm 0.1$ meV.