Composite fermions in periodic and random antidot lattices

Creators: Smet, J. H.; Weiss, D.; von Klitzing, K.; Coleridge, P. T.; Wasilewski, Z. W.; Bergmann, R.; Schweizer, H.; Scherer, A.

Abstract

The longitudinal and Hall magnetoresistance of random and periodic arrays of artificial scatterers, imposed on a high-mobility two-dimensional electron gas, were investigated in the vicinity of Landau level filling factor ν=1/2. In periodic arrays, commensurability effects between the period of the antidot array and the cyclotron radius of composite fermions are observed. In addition, the Hall resistance shows a deviation from the anticipated linear dependence, reminiscent of quenching around zero magnetic field. Both effects are absent for random antidot lattices. The relative amplitude of the geometric resonances for opposite signs of the effective magnetic field and its dependence on illumination illustrate enhanced soft wall effects for composite fermions.

Additional Information

© 1997 The American Physical Society. Received 27 March 1997. We are indebted to R. Fleischmann for enlightening discussions, P. Zawadski for initial sample characterization, and H. Grabeldinger, M. Riek, B. Schonherr, and U. Waizmann for help with sample preparation. This work has been supported by the Bundesministerium fur Bildung und Forschung, the European Community project "Human Capital and Mobility, Physics in High Magnetic Fields," the European Canadian Mesoscopics Initiative, and a NATO Collaborative Research Grant. The transport measurements at high magnetic fields were carried out in part at the National High Magnetic Field Laboratory sponsored by the National Science Foundation and the state of Florida.

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