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Resistance noise scaling in a 2D system in GaAs

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 نشر من قبل L'Hote
 تاريخ النشر 2004
  مجال البحث فيزياء
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The 1/f resistance noise of a two-dimensional (2D) hole system in a high mobility GaAs quantum well has been measured on both sides of the 2D metal-insulator transition (MIT) at zero magnetic field (B=0), and deep in the insulating regime. The two measurement methods used are described: I or V fixed, and measurement of resp. V or I fluctuations. The normalized noise magnitude SR/R^2 increases strongly when the hole density is decreased, and its temperature (T) dependence goes from a slight increase with T at the largest densities, to a strong decrease at low density. We find that the noise magnitude scales with the resistance, SR /R^2 ~ R^2.4. Such a scaling is expected for a second order phase transition or a percolation transition. The possible presence of such a transition is investigated by studying the dependence of the conductivity as a function of the density. This dependence is consistent with a critical behavior close to a critical density p* lower than the usual MIT critical density pc.



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We have measured the resistance noise of a two-dimensional (2D)hole system in a high mobility GaAs quantum well, around the 2D metal-insulator transition (MIT) at zero magnetic field. The normalized noise power $S_R/R^2$ increases strongly when the h ole density p_s is decreased, increases slightly with temperature (T) at the largest densities, and decreases strongly with T at low p_s. The noise scales with the resistance, $S_R/R^2 sim R^{2.4}$, as for a second order phase transition such as a percolation transition. The p_s dependence of the conductivity is consistent with a critical behavior for such a transition, near a density p* which is lower than the observed MIT critical density p_c.
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