Tunable electron heating induced giant magnetoresistance in the high mobility GaAs/AlGaAs 2D electron system

Electron-heating induced by a tunable, supplementary dc-current (I(dc)) helps to vary the observed magnetoresistance in the high mobility GaAs/AlGaAs 2D electron system. The magnetoresistance at B = 0.3 T is shown to progressively change from positive to negative with increasing I(dc), yielding negative giant-magnetoresistance at the lowest temperature and highest I(dc). A two-term Drude model successfully fits the data at all I(dc) and T. The results indicate that carrier heating modifies a conductivity correction σ(1), which undergoes sign reversal from positive to negative with increasing I(dc), and this is responsible for the observed crossover from positive- to negative- magnetoresistance, respectively, at the highest B.