Scaling in the metal-insulator transition of the fractional quantum Hall effect

Abstract

We study the magnetoresistance of a high-mobility two-dimensional electron gas at mK temperatures. In particular, the metal-insulator transitions between two adjacent fractional quantum Hall states ( 3 5 – 2 3 ) and between an integral and a fractional quantum Hall plateau ( 2 3−1 , 1−4 3 and 5 3−2 ) are investigated. We obtain a scaling behaviour of the width Δ B of the transition region as a function of the temperature T: ΔB ∝ T k , for T below a characteristic temperature T c. Within the experimental error, the exponent κ is the same for all the transitions and is found to be in the range from 0.40 to 0.45. These findings agree with the results of recent theoretical studies. We study the effect of tilted magnetic fields on the scaling behaviour and find a considerable influence of the electronic spin.