The effect of carrier density gradients on magnetotransport data measured in Hall bar geometry

We have measured magnetotransport of the two-dimensional electron gas in a Hall bar geometry in the presence of small carrier density gradients. We find that the longitudinal resistances measured at both sides of the Hall bar interchange by reversing the polarity of the magnetic field. We offer a simple explanation for this effect and discuss implications for extracting conductivity flow diagrams of the integer quantum Hall effect.Comment: 7 pages, 8 figure

Experimental Determination of the Subband Electron Effective Mass in InGaAs/InAlAs HEMT-structures by the Shubnikov – de Haas Effect at Two Temperatures

AbstractThe electron effective masses m* in different dimensionally quantized subbands in InGaAs/InAlAs HEMT-structures have been measured by the Shubnikov – de Haas effect at two temperatures whose ratio was not equal to 2. The electron effective masses were found separately for the every subband. It was realized by digital bandpass filtering of the Shubnikov – de Haas oscillation to monochromatic oscillations corresponding to subbands. We obtained the dependence of m* in every subband on InAs content in quantum well