Strong, ultranarrow peaks of longitudinal and Hall resistances in the regime of breakdown of the quantum Hall effect

With unusually slow and high-resolution sweeps of magnetic field, strong ultranarrow (width down to 100 mu T) resistance peaks an observed when high currents are applied through quantum Hall samples. The peaks are dependent on the directions and even the history of magnetic field sweeps, indicating the involvement of a very slow physical process. Such a process and the sharp peaks are, however, not predicted by existing theories. We also find that the sharp resistance peaks are influenced by the nuclear spin flips.