Suppressed Auger scattering and tunable light emission of Landau-quantized massless Kane electrons

The Landau level laser was proposed long ago as a unique source of monochromatic radiation that would be widely tunable in the THz and infrared spectral ranges using a magnetic field. However, despite many efforts, this appealing concept never progressed to the design of a reliable device. This is because of the efficient Auger scattering of Landau-quantized electrons, an intrinsic non-radiative recombination channel that eventually gains over cyclotron emission in all materials studied so far (conventional semiconductors with parabolic bands, but also in graphene with massless electrons). Auger processes are favoured in these systems because the Landau levels (or their subsets) are equally spaced in energy. Here, we show that this scheme does not apply to massless Kane electrons in gapless HgCdTe, where undesirable Auger scattering is strongly suppressed and sizeable cyclotron emission is observed. The gapless HgCdTe thus appears as a material of choice for future Landau level lasers.