Fractional quantum Hall effect at Landau level filling ν=4/11

We report low-temperature electronic transport results on the fractional quantum Hall effect of composite fermions at Landau level filling ν=4/11 in a very high mobility and low density sample. Measurements were carried out at temperatures down to 15mK, where an activated magnetoresistance Rxx and a quantized Hall resistance Rxy, within 1% of the expected value of h/(4/11)e2, were observed. The temperature dependence of the Rxx minimum at 4/11 yields an activation energy gap of ∼7mK. Developing Hall plateaus were also observed at the neighboring states at ν=3/8and5/13.