Nonlinear magnetotransport in a two-dimensional electron system with anisotropic mobility

Nonlinear magnetotransport of two-dimensional electrons in modulation-doped GaAs/AlAs heterostructures with anisotropic mobility is investigated. The mobility attains its maximum and minimum values in the $[1\overline{1}0]$ and [110] directions, respectively. It is found that, upon an increase in the direct electrical current $I_{dc}$ though Hall bars oriented along the [110] direction, the transition of the two-dimensional system to the state with differential resistance $r_{xx} \approx 0$ in a magnetic field occurs at a lower value of $I_{dc}$ and is accompanied by a more pronounced “plunge” into the region of negative $r_{xx}$ values as compared to bars oriented along the $[1\overline{1}0]$ direction. The results are explained by the impact of mobility on the spectral diffusion of nonequilibrium charge carriers.