Browsing by Author "Lee, B. C."

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Edge magnetoplasma excitations in quantum wire arrays
(2008-03-01)
Hsieh, W. H.
;
Suen, Y. W.
;
Lee, B. C.
;
Li, L. C.
;
Lee, C. P.
We report the low-temperature microwave properties of edge magneto-plasma excitations in quantum-wire arrays, fabricated from a two-dimensional electron gas in a GaAs/AlGaAs heterostructure and embedded in the slots of a 50-Omega meandering coplanar waveguide. The plot of frequency versus Landau level filling factors with strong absorption gives a series of barn-shaped curves with tops being centered in the quantum Hall effect plateaus and following a straight line through the origin. Away from the plateau center, the absorption dip becomes weaker and disappears near the plateau-plateau transition regime, qualitatively following the magneto hydrodynamic model. At frequencies above this barn-shaped part, however, we also observed unexpected resonant dips. (c) 2007 Published by Elsevier B.V.
Microwave-induced DC currents in mesoscopic structures
(2010-02-01)
Li, L. C.
;
Sung, Y. T.
;
Chang, C. W.
;
Suen, Y. W.
;
Chen, K. Y.
We report the power (P) dependence of microwave (MW)-induced current (I(ph)) of a 1-mu m sized mesoscopic structure fabricated from two-dimensional electron gas in the GaAs/AlGaAs heterostructure at temperature of 1.4 K. MW signals were fed onto the sample through a loop antenna nearby and I(ph) is measured from a pair of ohmic contacts. We found that I(ph) is proportional to P at low-P limit; this dependence has been predicted for diffusion-limited electron transport in mesoscopic systems. By contrast, for large P. the dependence is extremely non-monotonous and complicated; even though its physical origin is still not clear so far, our data suggest it is related to the scattering processes from boundaries and impurities in the mesoscopic structure. We also investigated the symmetry properties against reversal of magnetic field (B) and found that the field-symmetric part of I(ph)(B) is consistent with the variation of magnetoresistance; there exists also an anti-symmetric part, which should be related to time-reversal-symmetry-breaking scattering mechanisms in the channel. (C) 2009 Elsevier B.V. All rights reserved.