Direct measurement of critical exponents in the quantum Hall regime

S. Koch, R. J. Haug, K. von Klitzing, K. Ploog

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


We have studied the magnetoresistance of AlGaAs/GaAs-heterojunctions at millikelvin temperatures in small Hall bar and Corbino geometries with different sizes. Below a characteristic temperature Tc which increases with decreasing sample width, the phase-breaking length Lin is larger than the sample size. Under these conditions the half width ΔB of the longitudinal magnetoresistance no longer depends upon temperature but only upon size. By varying the size it is thus possible to directly investigate the localization transition in the integer quantum Hall regime and to measure the critical exponent v of the localization length ξ α |B - Bc|-v. Our results show a universal behaviour in the three lowest Landau levels. This is in agreement w universality statement of the field-theoretic approach to the metal-insulator transition in the quantum Hall effect. By studying the characteristic temperature Tc for different widths, the temperature exponent p 2 of the inelastic scattering length can also be measured.

Original languageEnglish (US)
Pages (from-to)108-111
Number of pages4
JournalSurface Science
Issue number1-3
StatePublished - Feb 19 1992

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Materials Chemistry


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