Professor Andrew Turberfield

Abstract:

We report resonant inelastic light scattering measurements of collective electronic excitations at filling factor v = 1/3 in a high mobility 2DES at temperatures between 50 mK and 3 K. In a narrow range of temperatures near 1 K the intensity of light scattering from the charge density mode, and the exchange enhancement of the energy of a collective spin excitation, fall rapidly to zero. We deduce that the electron correlation characteristic of the spin-polarized electron liquid at v = 1/3 collapses at 1 K: this collapse is triggered by thermal fluctuations of the electron spin. (C) 1998 Elsevier Science B.V. All rights reserved.

Abstract:

We present measurements of photoluminescence from the incompressible two-dimensional electron system at filling factor v = 1. By varying the doping density, sample structure and angle between magnetic field and confinement plane we investigate the influence of electron-electron and electron-valence hole interactions on the photoluminescence spectrum. We find that a strong electron-valence hole interaction suppresses a characteristic discontinuity in the photoluminescence energy. In all samples studied the electron-valence hole interaction is strong enough to prevent observation of a theoretically predicted tilt-induced shrinkage of skyrmion-charged spin texture excitations. (C) 1998 Elsevier Science B.V. All rights reserved.

Abstract:

Inelastic light scattering from 2D electrons below 100 mK reveals collective charge and spin density excitations of the incompressible electron liquid at Landau level filling factor ν = 1/3 and provides experimental evidence for a magnetoroton minimum in the charge density dispersion curve. The temperature scale for the collapse of electron correlation in the spin-polarized electron liquid is determined by thermal excitation of long-wavelength spin waves. © 1997 The American Physical Society.