Publications
New results of ultra-low temperature experiments in the second Landau level of a two-dimensional electron system
In the second Landau level around {nu} = 5/2 filling of an extremely high quality 2D electron system and at temperatures T down to 9 mK we observe a very strong even-denominator fractional quantum Hall effect at Landau level filling {nu} = 5/2 and its energy gap is large and {Delta} {approx} 0.45 K. A clear FQHE state is seen at {nu} = 2+2/5, with well-quantized R{sub xy}. A novel, even denominator FQHE state at {nu} = 2+3/8 seems to develop, as deduced from the T-dependence of dR{sub xy}/dB. In addition, four fully developed re-entrant integral quantum Hall effect (RIQHE) states are also observed. At low temperatures, the wide RIQHE plateau around at {nu} = 2+2/7 is interrupted by a dip, indicating an additional reentrance. Finally, the tilted magnetic field experiment at an ultra-low temperature of 10 mK was carried out to examine the spin-polarization of the {nu} = 5/2 FQHE state.