Improvement of the transport properties of a high-mobility electron   system by intentional parallel conductance
  We present a gating scheme to separate even strong parallel conductance from the magneto-transport signatures and properties of a two-dimensional electron system. By varying the electron density in the parallel conducting layer, we can study the impact of mobile charge carriers in the vicinity of the dopant layer on the properties of the two-dimensional electron system. It is found that the parallel conducting layer is indeed capable to screen the remote ionized impurity potential fluctuations responsible for the fragility of fractional quantum Hall states. 
Sebastian Peters, Lars Tiemann, Christian Reichl, Stefan F\"alt,   Werner Dietsche, Werner Wegscheider
cond-mat.mes-hall