Lb. Liao et al., INELASTIC LIGHT-SCATTERING STUDY OF MAGNETOPLASMA MODES IN A WIDE PARABOLIC QUANTUM-WELL, Physical review. B, Condensed matter, 49(23), 1994, pp. 16825-16828
Inelastic light scattering was used to study the dispersion and magnet
ic-field dependence of both inter-Landau and intersubband magnetoplasm
a modes in a wide parabolic quantum well. The intersubband magnetoplas
mon energy (approximately 11 meV) was found to be much greater than ex
pected from a simple self-consistent Hartree calculation (approximatel
y 2 meV). The value is in fact very close to the bare harmonic energy
of the well. This striking example of the absence of corrections to th
e single-particle energy from electron-electron interactions is the re
sult of Kohn's theorem. In a magnetic field, the intersubband magnetop
lasmon energy is constant except at the field where the inter-Landau e
nergy crosses the intersubband energy. After the crossover, the inters
ubband energy shifts to a lower value. This is interpreted as a shift
in oscillator strength from a bulklike to a surfacelike magnetoplasma
mode.