QUASI-ELASTIC INTERLANDAU-LEVEL SCATTERING IN SAMPLES WITH ROTATIONAL SYMMETRY

For relatively wide ring-shaped samples, a current dependence of the magnetoresistance has been observed that closely resembles previously published results for rectangular samples with narrow constrictions. The latter results had been quantitatively explained as being due to a specific breakdown process for which the high current densities and the resulting strong Hall electric fields in the constrictions are essential. Since the widths of the rings were much larger than those of the constrictions in the rectangular samples, the similarity between the experimental results seems surprising. The previous calculations were made for a rectangular geometry and a homogeneous Hall electric field, whereas in a ring, one would expect the field to increase towards the inner edge. To check whether this may remove the discrepancy, in this paper, corresponding formulae are derived for a ring-shaped geometry and compared with the experimental results. The discrepancy is found to be reduced, but not removed.