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Observation of Collective Excitations of the Dilute 2D Electron System

M. A. Eriksson·A. Pinczuk·B. S. Dennis·S. H. Simon·L. N. Pfeiffer·K. W. West
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Abstract

We report inelastic light scattering measurements of dispersive spin and charge density excitations in dilute 2D electron systems reaching densities less than 10^{10} cm^{-2}. In the quantum Hall state at nu=2, roton critical points in the spin inter--Landau level mode show a pronounced softening as r_s is increased. Instead of a soft mode instability predicted by Hartree--Fock calculations for r_s ~ 3.3, we find evidence of multiple rotons in the dispersion of the softening spin excitations. Extrapolation of the data indicates the possibility of an instability for r_s >~ 11.

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M. A. Eriksson, A. Pinczuk, B. S. Dennis, S. H. Simon, L. N. Pfeiffer, K. W. West. 1998-10-23. Observation of Collective Excitations of the Dilute 2D Electron System. https://doi.org/10.1103/physrevlett.82.2163

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