Abstract
We report on the clear evidence of massless Dirac fermions in two-dimensional system based on III-V semiconductors. Using a gated Hall bar made on a three-layer InAs/GaSb/InAs quantum well, we restore the Landau level fan chart by magnetotransport and unequivocally demonstrate a gapless state in our sample. Measurements of cyclotron resonance at different electron concentrations directly indicate a linear band crossing at the point of the Brillouin zone. Analysis of experimental data within an analytical Dirac-like Hamiltonian allows us not only to determine the velocity (v F = 1.8 × 10 5 m/s) of massless Dirac fermions, but also to demonstrate a significant nonlinear dispersion at high energies.