From insulator to quantum Hall liquid at low magnetic fields
  We have performed low-temperature transport measurements on a GaAs two-dimensional electron system at low magnetic fields. Multiple temperature-independent points and accompanying oscillations are observed in the longitudinal resistivity between the low-field insulator and the quantum Hall (QH) liquid. Our results support the existence of an intermediate regime, where the amplitudes of magneto-oscillations can be well described by conventional Shubnikov-de Haas theory, between the low-field insulator and QH liquid. 
Tsai-Yu Huang, C.-T. Liang, Gil-Ho Kim, C. F. Huang, Chao-Ping Huang,   Jyun-Ying Lin, Hsi-Sheng Goan and D. A. Ritchie