Insulating and fractional quantum hall states in the first excited Landau level.

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