Longitudinal resistivity in the quantum Hall effect regime in a split‐gate Si MOSFET with variable electron density

Abstract

AbstractLongitudinal resistivity in the quantum Hall effect regime was measured in a Si MOSFET sample in which split‐gate allows to vary the electron density and filling factor in different parts of the sample. In case of equal gate voltages on both sides of the split, the resistance, measured across the split in zero and weak magnetic fields, is larger due to electron scattering by split‐induced potential barrier. However, in strong magnetic fields, the additional resistance disappears because the current flows mostly via the edge channels along the equipotential curves. In case of different gate voltages, the longitudinal resistance is different for opposite sides of the sample because the Hall voltage difference is added only to one side of the sample depending on the sign of the gradient of gate voltages and magnetic field direction. An increase of longitudinal resistance was observed when electrons across the split occupy Landau levels with opposite spin orientation. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)