Gunn effect in InSb in a magnetic field

The apparent threshold electric field for the onset of bulk negative differential conductivity (BNDC) is reduced markedly in a transverse magnetic field. In addition, the threshold for onset of a high-conductivity instability triggered by the generation of a dense electron-hole plasma in the wake of a single-transiting high-electric-field domain is also reduced by the magnetic field. This reduction in thresholds is due to field constriction at the sample corners caused by shorting of the Hall electric field by the contacts. The high-electric-field domains are nucleated in the high-field regions at the sample corners, thus causing BNDC to occur at a lower average electric field. These results are obtained by potential probing and Hall measurements on nanosecond time scales.