Journal Article

Terahertz cyclotron emission from two-dimensional Dirac fermions

Consejo, C, Ruffenach, S, Torres, J, Krishtopenko, S. S, Ballet, P, Orlita, M, Gavrilenko, V. I, Dvoretskii, S. A, Teppe, F, Gebert, S, Bray, C, Jouault, B, Morozov, S. V, Baudry, X, Mikhailov, N. N, Szola, M

2023

Overview

Since the emergence of graphene, we have seen several proposals for the realization of Landau lasers tunable over the terahertz frequency range. The hope was that the non-equidistance of the Landau levels from Dirac fermions would suppress the harmful non-radiative Auger recombination. Unfortunately, even with this non-equidistance, an unfavourable non-radiative process persists in Landau-quantized graphene, and so far no cyclotron emission from Dirac fermions has been reported. One way to eliminate this last non-radiative process is to sufficiently modify the dispersion of the Landau levels by opening a small gap in the linear band structure. HgTe quantum wells close to the topological phase transition are a proven example of such gapped graphene-like materials. In this work we experimentally demonstrate Landau emission from Dirac fermions in such HgTe quantum wells, where the emission is tunable by both the magnetic field and the carrier concentration. Consequently, these results represent an advance in the realization of terahertz Landau lasers tunable by a magnetic field and gate voltage.Two-dimensional massive and massless Dirac fermions in HgTe/CdHgTe quantum wells yield terahertz Landau emission. The emission frequency is continuously tunable with magnetic field or carrier concentration, over the range from 0.5 to 3 THz.

• Publisher: Nature Publishing Group
• Subject: Augers / Carrier density / Cyclotrons / Electrons / Emission / Fermions / Frequency ranges / Graphene / Lasers / Magnetic fields / Mercury tellurides / Phase transitions / Quantum wells / Recombination / Terahertz frequencies / Wells