Insulating and Fractional Quantum Hall States in the N=1 Landau Level

J. P. Eisenstein, K. B. Cooper, L. N. Pfeiffer, K. W. West

Published 2001-10-22Version 1

The observation of new insulating phases of two-dimensional electrons in the first excited Landau level is reported. These states, which are manifested as re-entrant integer quantized Hall effects, exist alongside well-developed even-denominator fractional quantized Hall states at nu=7/2 and 5/2 and new odd-denominator states at nu=3+1/5 and 3+4/5.