Abstract
We have measured the current distribution in GaAs/AlGaAs two-dimensional electron system (2DES) at quantum Hall effect (QHE) regime to investigate the mechanism of QHE breakdown. A Hall-bar device on the scanning stage is locally illuminated by an infrared laser light guided by polarization maintaining optical fiber at QHE condition. We have tried to map the QHE breakdown critical current with local photo-excitation. The mapping of breakdown critical current shows the current concentration at the center region of 2DES channel in the sample where the critical current shows sub-linear dependence on the channel width. We have also tried to measure the Hall potential imaging in the electric current flowing 2DES by means of Pockels effect in GaAs/AlGaAs sample. The experimental techniques of the optical fiber based current distribution imaging in the high magnetic field up to 9 T have been reported in detail.
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