Nonlinear Transport of 2d Electrons in Magnetic Field

Abstract

Electric field induced, spectacular reduction of longitudinal resistivity of two dimensional electrons placed in strong magnetic field is studied in broad range of temperatures. The data are in good agreement with theory, considering the strong nonlinearity of the resistivity as result of non-uniform spectral diffusion of 2D electrons induced by the electric field. Comparison with the theory gives inelastic scattering time τin of the 2D electrons. In temperature range T = 2 - 20 K for overlapping Landau levels, the inelastic scattering rate 1/τin is found to be proportional to T2, indicating dominant contribution of the electron-electron interaction to the inelastic electron relaxation. At strong magnetic field, at which Landau levels are well separated, the inelastic scattering rate is proportional to T3 at high temperatures. We suggest the electron-phonon scattering as the dominant mechanism of the inelastic electron relaxation in this regime. At low temperature and separated Landau levels an additional regime of the inelastic electron relaxation is observed: τin ~ T-1.26.