Insulating phase of a two-dimensional electron gas in MgZnO/ZnO   heterostructure below nu = 1/3
  We report magnetotransport properties of a two-dimensional electron gas confined at MgZnO/ZnO heterointerface in a high magnetic field up to 26 T. High electron mobility and low charge carrier density enabled the observation of the fractional quantum Hall state nu = 1/3. For an even lower charge carrier density, we observe a transition from quantum Hall liquid to an insulator below the filling factor 1/3. Because of the large electron effective mass in ZnO, we suggest the MgZnO/ZnO heterostructure to be a prototype system for highly correlated quantum Hall physics. 
Y. Kozuka, A. Tsukazaki, D. Maryenko, J. Falson, S. Akasaka, K.   Nakahara, S. Nakamura, S. Awaji, K. Ueno, and M. Kawasaki
cond-mat.mes-hall