Absence of Scaling in the Integer Quantum Hall Effect

Abstract

We have studied the conductivity peak in the transition region between the two lowest integer Quantum Hall states using transmission measurements of edge magnetoplasmons. The width of the transition region is found to increase linearly with frequency but remains finite when extrapolated to zero frequency and temperature. Contrary to prevalent theoretical pictures, our data does not show the scaling characteristics of critical phenomena. These results suggest that a different mechanism governs the transition in our experiment. PACS numbers:73.20.Mf; 73.40.HmIn highly disordered samples, the integer Quantum Hall Effect (IQHE) shows broad regions in magnetic field, B, where the longitudinal conductivity, σxx, vanishes, while the Hall conductance, σxy, is quantized in units of e 2 /h. In the transition regions, σxy goes from one quantized plateau to the next while σxx goes through a peaked value and decreases again. Theoretically, this behavior was explained using the scaling theory of localization [1, 2]. The peak conductance occurs when the chemical potential, µ, crosses the extended state at energy Ec, in the middle of the Landau level (LL). Near this energy

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