Spin and Charge Density Excitations and the Collapse of the Fractional Quantum Hall State atν=1/3

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 $\ensuremath{\nu}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1/3$ 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.