Resistance hysteresis in the integer and fractional quantum Hall regime

We present experimental results where hysteresis is observed depending on the magnetic field sweep direction in the integer quantum Hall regime of a high-mobility two-dimensional electron system formed in a GaAs/AlGaAs heterostructure. We analyze the results based on the screening theory and show that the anomalous effects observed stem from the nonequilibrium processes resulting from the formation of metal-like and insulator-like regions due to direct Coulomb interactions and the dissipative nature of the Hall bar together with the scattering-influenced contacts. Furthermore, the hysteretic behavior is shown for the integer filling factors ν=1, 2, and 4 and for certain fractional states at the longitudinal resistance. We argue that the nonequilibration is not only due to contacts, in contrast, but also due to the nature of the finite size dissipative Hall bar under interactions and Landau quantization.