Quantum Hall effect induced by electron-electron interaction in disorderedGaAs layers with a three-dimensional spectrum

It is shown that the observed quantum Hall effect in epitaxial layers of he avily doped ii-type GaAs with thickness (50-140 nm) larger the mean free pa th of the conduction electrons (15-30 nm) and, therefore, with a three-dime nsional single-particle spectrum is induced by the electron-electron intera ction. The Hall resistance R-xy of the thinnest sample reveals a wide plate au at small activation energy E-a = 0.4 K found in the temperature dependen ce of the transverse resistance R-xx. The different minima in the transvers e conductance G(xx) of the different samples show a universal temperature d ependence (logarithmic in a large range of rescaled temperatures T/T-0)that is reminiscent of electron-electron-interaction effects in coherent diffus ive transport. [S0163-1829(99)09211-5].