Optical probing of the metal-to-insulator transition in a two-dimensional high-mobility electron gas

We study the quantum Hall liquid and the metal–insulator transition in a high-mobility two-dimensional electron gas, by means of photoluminescence and magnetotransport measurements. In the integer and fractional regime at nu > 1/3, by analyzing the emission energy dispersion we probe the magneto-Coulomb screening and the hidden symmetry of the electron liquid. In the fractional regime above nu = 1/3, the system undergoes metal-toinsulator transition, and in the insulating phase the dispersion becomes linear with evidence of an increased renormalized mass.