CHINESE JOURNAL OF PHYSICS VOL. 39, NO. 4 AUGUST 2001

Letter

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

C.-T. Liang, C. F. Huang, Yu-Ming Cheng, Tsai-Yu Huang, Y. H. Chang and Y. F. Chen

Department of Physics, National Taiwan University, Taipei 106, Taiwan R.O.C.
(Received June 13, 2001)

We have performed low-temperature transport experiments on a Si/SiGe hole system. The measured transverse and longitudinal conductivities $\sigma_{xy}$ and $\sigma_{xx}$ 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 $\rho _{xx}(B)$, $\rho _{xy}(B)$, $\sigma_{xx}(B)$, and $\sigma _{xy}(B)$ which corresponds to a boundary of the quantum phase transition.

PACS. 73.40.-c - Electronic transport in interface structures.
PACS. 73.43.-f - Quantum Hall effects.
PACS. 73.43.Nq - Quantum phase transitions.

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