nu=5/2 Fractional Quantum Hall State in the Presence of Alloy Disorder

Aschannel of a quantum well. We nd that the = 5=2 state is suppressed with alloy scattering. To oursurprise, in samples with alloy disorder the = 5=2 state appears at signi cantly reduced mobilitieswhen compared to samples in which alloy disorder is not the dominant scattering mechanism. Ourresults highlight the distinct roles of the di erent types of disorder present in these samples, suchas the short-range alloy and the long-range Coulomb disorder.