GaAs heterostructures at mK temperatures and fractional filling factors

Transport experiments in high mobility (110) GaAs heterostructures have been performed at very low temperatures (View the MathML source). At higher Landau-levels we observe a transport anisotropy that bears some similarity with what is already seen at half-odd-integer filling on (001) oriented substrates. In addition we report the first observation of transport anisotropies within the lowest Landau-level. An unprecedented feature of this new anisotropy is a dependence on the polarity of the magnetic field.