Fermi liquid behavior of metallic 2D holes at high temperatures

The resistivity $\rho$ of high mobility dilute 2D holes in GaAs exhibits a peak at a certain temperature $T^*$ in zero magnetic field($B$=0). In the $T>T^*$ regime where d$\rho$/d$T<$0, we observe for the first time both the $\nu=1$ quantum Hall(QH) effect and a low field insulator-QH transition which is consistent with the 2D hole system being a Fermi liquid(FL). The known linear $T$-dependent conductivity in this $T$ regime then can be explained by hole-hole Coulomb interactions of this FL. The fact that the system is metallic (d$\rho$/d$T>$0) for $T<T^*$ implies that the high temperature FL transforms into the 2D metallic state in the neighborhood of $T^*$.