On the thermal broadening of a quantum critical phase transition

The temperature dependence of an integer Quantum Hall effect transition is studied in a sample where the disorder is dominated by short-ranged potential scattering. At low temperatures the results are consistent with a $(T/T_0)^{\kappa}$ scaling behaviour and at higher temperatures by a linear dependence similar to that reported in other material systems. It is shown that the linear behaviour results from thermal broadening produced by the Fermi-Dirac distribution function and that the temperature dependence over the whole range depends only on the scaling parameter T$_0^{\kappa}$.