Observation of fractional quantum Hall effect at even-denominator 1/2 and 1/4 fillings in asymmetric wide quantum wells

J. Shabani, T. Gokmen, Y. T. Chiu +1

We report the observation of developing fractional quantum Hall states at Landau level filling factors $\nu =1/2$ and 1/4 in electron systems confined to wide GaAs quantum wells with…