Showing papers by "Aron Pinczuk published in 1998"
TL;DR: Inelastic light scattering by low-energy spin-excitations reveals three distinct configurations of spin of electron double layers in gallium arsenide quantum wells at even-integer quantum Hall states, providing direct evidence of a link between quantum phase transitions and soft collective excitations in a two-dimensional electron system.
Abstract: Inelastic light scattering by low-energy spin-excitations reveals three distinct configurations of spin of electron double layers in gallium arsenide quantum wells at even-integer quantum Hall states. The transformations among these spin states appear as quantum phase transitions driven by the interplay between Coulomb interactions and Zeeman splittings. One of the transformations correlates with the emergence of a spin-flip intersubband excitation at vanishingly low energy and provides direct evidence of a link between quantum phase transitions and soft collective excitations in a two-dimensional electron system.
65 citations
TL;DR: In this article, the collective gap mode of the fractional quantum Hall liquid has been used to obtain measurements of low-lying collective excitations of the 2D electron gas at Landau level filling ν = 1 3, where l 0 is the magnetic length.
Abstract: Resonant inelastic scattering methods give access to measurements of low-lying collective excitations of the 2D electron gas at Landau level filling ν= 1 3 . In experiments at finite light scattering wave vectors | k |=k⩽0.15 l 0 −1 , where l0 is the magnetic length, we find strong light scattering by the collective gap mode of the fractional quantum Hall liquid. Long wavelength spin waves also become allowed in the tilted-field configuration of the present experiments. Such measurements enable the exploration of dispersive charge- and spin-excitations. The energies of the long wavelength collective gap mode at ν= 1 3 display a square-root dependence on perpendicular magnetic field in agreement with current theories of the incompressible quantum fluid. We also consider weaker spectra assigned to light scattering by large wave vector spin wave and collective gap excitation modes. These features are associated with breakdown of wave vector conservation in resonant inelastic light scattering.
18 citations
TL;DR: In this article, the authors performed high-resolution, polarized photoluminescence (PL) experiments on a high-mobility GaAs/AlGaAs single quantum well near ν=1.
Abstract: We perform high-resolution, polarized photoluminescence (PL) experiments on a high-mobility GaAs/AlGaAs single quantum well near ν=1. Upon entering the ν=1 quantum-Hall region the PL shows a remarkable polarization dependence. For RCP polarization the PL exhibits the usual reduction of the peak intensity, and a cusp in the spectral energy of the peak. For LCP polarization we observe unanticipated novel behavior: a major change in the PL line shape, and the development of two new peaks, one above and one below the main emission peak. This large asymmetry between RCP and LCP polarizations can be modeled by considering the initial spin-configuration prior to the recombination of the e–h pair. Among the models consistent with our observations are a “shake-up” process in which finite-momentum spin waves are generated in the electron system upon recombination in the LCP polarization.
3 citations