Optical Anomalies of the Two-Dimensional Electron Gas in the Extreme Magnetic Quantum Limit

Abstract

Band-gap optical recombination from the two-dimensional electron gas in GaAs-(Al,Ga)As quantum wells was measured in the regime of the fractional quantum Hall effect. New intrinsic emission lines emerge at the Landau-level filling factor $\nu \lesssim 1$ and at $\nu <0.8\mathrm{}$. The anomaly near $\nu =1\mathrm{}$ is associated with changes in population of the lowest spin-split Landau level. The spectral doublet observed near $\nu =\frac{2}{3}$ has a striking temperature dependence below $T=2\mathrm{}$ K similar to the magnetoresistance ${\rho }_{\mathrm{xx}}$ associated with the many-body quantum fluid.