Experiments on Delocalization and University in the Integral Quantum Hall Effect

Abstract

We find that the transport coefficients ${\ensuremath{\rho}}_{\mathrm{xy}}$ and ${\ensuremath{\rho}}_{\mathrm{xx}}$ of two-dimensional electrons in InGaAs/InP show a characteristic power-law dependence on $T$. In the range $0.1 \mathrm{K} \ensuremath{\lesssim}T\ensuremath{\lesssim} 4.2 \mathrm{K}$, the maximum of $\frac{d{\ensuremath{\rho}}_{\mathrm{xy}}}{\mathrm{dB}}$ diverges like $\ensuremath{\sim}{T}^{\ensuremath{-}\ensuremath{\kappa}}$ with $\ensuremath{\kappa}=0.42\ifmmode\pm\else\textpm\fi{}0.04$, for Landau levels $N=0\ensuremath{\downarrow}$, $1\ensuremath{\uparrow}$, and $1\ensuremath{\downarrow}$, and the half-width $\ensuremath{\Delta}B$ for ${\ensuremath{\rho}}_{\mathrm{xx}}$ vanishes as $\ensuremath{\Delta}B\ensuremath{\sim}{T}^{\ensuremath{\kappa}}$. These results confirm the prediction of the scaling theory that the characteristic power-law behavior in the transport coefficients is a universal feature of delocalization in the integral quantum Hall effect.