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quantum Hall insulator; far-infrared excitation
Abstract:
The transition of two-dimensional electron systems (2DES) with
intentional disorder in form of a delta-layer doped with
beryllium into quantum Hall insulators composed of separate
electron droplets is examined by magnetotransport and far-
infrared spectroscopy. We observe the percolation threshold at
filling factors clearly below nu(c) = (1)/(2) that is expected
for statistical disorder. The far-infrared excitations bear
strong resemblance to magnetoplasmons of density-modulated 2DES
and antidot systems in regular arrays. Thus, a perceptible
degree of short-range order between the sites of the beryllium
acceptors is uncovered. (C) 2002 Elsevier Science B.V. All
rights reserved.
