Browsing by Author "Du, R.R."

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    Enhancement of the v=5/2 Fractional Quantum Hall State in a Small In-Plane Magnetic Field
    (American Physical Society, 2012) Liu, Guangtong; Zhang, Chi; Tsui, D.C.; Knez, Ivan; Levine, Aaron; Du, R.R.; Pfeiffer, L.N.; West, K.W.
    Using a 50-nm-width ultraclean GaAs=AlGaAs quantum well, we have studied the Landau level filling factor v=5/2 fractional quantum Hall effect in a perpendicular magnetic field B 1:7 Tand determined its dependence on tilted magnetic fields. Contrary to all previous results, the 5=2 resistance minimum and the Hall plateau are found to strengthen continuously under an increasing tilt angle 0< <25 (corresponding to an in-plane magnetic field 060 , and the composite fermion series [2 þ p=ð2p 1Þ, p ¼ 1; 2] can be identified. Based on our results, we discuss the relevance of a Skyrmion spin texture at v= 5/2 associated with small Zeeman energy in wide quantum wells, as proposed by Wo´js et al
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    Millimeter wave transmission spectroscopy of gated two-dimensional hole systems
    (American Institute of Physics, 2012) Stone, K.; Du, R.R.; Manfra, M.J.; Pfeiffer, L.N.; West, K.W.
    We developed a differential transmission to study cyclotron resonance of GaAs/AlxGa1 xAs two-dimensional hole samples. The technique utilizes a modulated AuPd gate isolated by a Si3N4 dielectric from the sample, which is irradiated opposite the gate by millimeter waves ranging from 2 to 40GHz. This technique effectively removes the background signal and yields a hole effective mass of 0:41me with a cyclotron scattering time of 20 ps, consistent with the previous results using different techniques.