Observation of a Fractional Quantum Hall State at ν=1/4 in a Wide GaAs Quantum Well

We report the observation of an even-denominator fractional quantum Hall state at nu=1/4 in a high quality, wide GaAs quantum well. The sample has a quantum well width of 50 nm and an electron density of n(e)=2.55x10(11) cm(-2). We have performed transport measurements at T similar to 35 mK in magnetic fields up to 45 T. When the sample is perpendicular to the applied magnetic field, the diagonal resistance displays a kink at nu=1/4. Upon tilting the sample to an angle of theta=20.3 degrees a clear fractional quantum Hall state emerges at nu=1/4 with a plateau in the Hall resistance and a strong minimum in the diagonal resistance.