Hall Effect of an Inhomogeneous Material

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Abstract
The effective Hall mobility is calculated for a material containing inclusions which have a conductivity and Hall mobility differing from those of the matrix in order to investigate whether Hall‐effect‐Seebeck‐effect anomalies can be explained by the presence of inclusions. The calculation is performed analytically using a method by which Airapetiants has determined the effect of inclusions on the Seebeck effect, and numerically by solution of the Laplace equation with the relaxation method. The effective Hall mobility is largely dependent on the ratio of the specific conductivity of the inclusion to that of the matrix. The possibility of obtaining a sign reversal of the Hall effect when the Hall effects of matrix and inclusion have opposite sign is largest when the respective conductivities are about equal. The Hall effect anomaly occurring in Li‐doped NiO at 600 °K might be explained by assuming that 1% inclusions having a negative Hall effect with a Hall mobility of ≈ 5 cm2/V sec are present. However, this explanation requires the specific conductivity of the inclusions to be proportional to the Li concentration which seems improbable. It is shown to be impossible to explain the Hall‐effect‐Seebeck‐effect anomaly of chalcogenide glasses with the present model.