Temperature dependence of the quantum Hall resistance

High precision measurements of the temperature dependence of the quantum Hall resistance for a GaAs/GaAlAs heterostructure are reported. Our data agree with the results of Cage et al. [Phys. Rev. B30 (1984) 2286] concerning the linear relationship between ρxy(T) and ρxx(T) in the temperature range 1.5 < T < 4.2 K. In addition to being device dependent this effect was found to be strongly cool-down dependent for our samples.