Thickness variations and the Corbino effect

Abstract
We examined the effect of thickness variations in Corbino samples of very pure aluminum at 4.2 K in magnetic fields up to 7 T. Only thickness variations that affect the axial symmetry of the sample were found to perturb the Corbino current pattern and to lower the magnetoresistance. A simple model accounts for our data and also shows that the linear magnetoresistance, observed for simple metals in earlier experiments in the Corbino geometry, may have been caused by unintentional variations in thickness.