Résumé
In this work, we report on experimental and theoretical studies of magnetic field-tunable terahertz cyclotron emission from high-quality MBE-grown Hg1-xCdxTe bulk films with different Cd concentrations in the composition. Due to their relativistic-like dynamics, their cyclotron mass strongly depends on temperature and Cd concentration. We demonstrate that the efficiency of magnetic field tuning increases for alloy compositions approaching the energy band gap closing condition (for Cd, x ~ 0.17 at 4 K) and reaches its maximum for linear - Dirac-like energy band dispersion. The record tune-ability above 4 THz/T, leading to 3 THz emission at magnetic fields around 0.5 T, is reported. Our results open new ways for developing efficient radiation sources and detectors designed for THz spectrometers controlled by slight magnetic fields.