Near-field scanning magneto-photoluminescence of composite fermions in In(Ga)P/GaInP quantum dots

Abstract

We measured spatial and magnetic field dependence of photoluminescence (PL) spectrum of In(Ga)P/GaInP quantum dots (QDs) having up to 8 electrons and quantum confinement ħω 0 down to 2 meV using low temperature (10K) near-field scanning optical microscope (NSOM) providing spatial resolution ∼20 nm and external magnetic field up to B0=10 T. Using these measurements we identified QDs having Wigner-Seitz radius up to 2 and internal magnetic field B int up to 15 T, corresponding to Landau level filling factor v at zero field ν 0 3, 5/2, 2/5 and 1/5. In magneto-PL spectra we observed features related to integer and fractional quantum Hall states and identified composite fermion (CF) states corresponding to Wigner molecule isomers (1, 5) and (0, 6). Our results demonstrate perspectives of using In(Ga)P/GaInP QD structures, providing deterministic localization of CFs in zero external magnetic field, in “magnetic-field-free” topological quantum gates.