Studies of the Temperature-Driven Flow Lines and Phase Transitions in a Two-Dimensional Si/SiGe Hole System

We have performed low-temperature transport experiments on a Si/SiGe hole system. The measured transverse and longitudinal condductivities ${\sigma }_{xx}$ and ${\sigma }_{xy}$ allow us to study the magnetic-field-induced transitions in the system. In particular, we present the first study of the temperature-driven flow lines in the “anomalous Hall insulator” regime near a Landau level filling factor $\nu =1.5$. The “anomalous” temperature-driven flow lines could be due to the unusual energy level scheme in a Si/SiGe hole system. Moreover, for $3<\nu <5$, there is a temperature-independent point in ${\rho }_{xx}(B)$, ${\rho }_{xy}(B)$, ${\sigma }_{xx}$, and ${\sigma }_{xy}$ which corresponds to a boundary of the quantum phase transition.