Nonmonotonic Temperature Dependence of the Hall Resistance for 2D   Electron System in Si
  Weak field Hall resistance Rxy(T) of the 2D electron system in Si was measured over the range of temperatures 1-35 K and densities, where the diagonal resistivity exhibits a ``metallic'' behavior. The Rxy(T) dependence was found to be non-monotonic with a maximum at temperatures Tm~0.16Tf. The Rxy(T) variations in the low-temperature domain (T<Tm) agree qualitatively with the semiclassical model, that takes into account a broadening of the Fermi-distribution solely. The semiclassical result considerably exceeds an interaction-induced quantum correction. In the ``high-temperature'' domain (T>Tm), the Rxy(T) dependence can be qualitatively explained in terms of either a semiclassical T-dependence of a transport time, or a thermal activation of carries from a localized band. 
A. Yu. Kuntsevich, D. A. Knyazev, V. I. Kozub, V. M. Pudalov, G.   Brunhaler, G. Bauer