EXPERIMENTS ON INELASTIC-SCATTERING IN THE INTEGER QUANTUM HALL-EFFECT

Using the temperature (T) dependence of the maximum slope of rho(xy) versus B in between two adjacent integer quantum Hall (IQH) plateaus as a thermometer for T<1.2 K, we study the effective temperature (T-e) of a two-dimensional electron gas as a function of applied current I in five GaAs/AlxGa1-xAs heterostructures with mobility ranging from 52 000 to 780 000 cm(2)/V s. We find that there is a characteristic current above which T-e similar to I-a and a=0.49+/-0.03 independent of Landau levels and electron mobilities. In the context of electron heating, our result demonstrates explicitly the existence of a universal T exponent p=2.1+/-0.24 for the inelastic scattering length in the IQH regime.