Electrical Properties ofp-Type Indium Antimonide at Low Temperatures

The electrical resistivity $\rho$, Hall coefficient $R$, and transverse magnetoresistive ratio $\frac{\Delta \rho }{\rho }$ of $p$-type single crystals of indium antimonide have been measured between 370°K and 1.5°K. Low-temperature anomalies similar to those observed by Hung on germanium have been found, a steep maximum in the $logR$ versus $\frac{1}{T}$ curve and a change of slope of the $log\rho$ versus $\frac{1}{T}$ curve. Contrary to the case with germanium, the magnetoresistive ratio of InSb does not vanish in the lowest temperature range, but it changes its sign from positive to negative as the sample is cooled to a temperature somewhat lower than that at which the Hall coefficient reaches its maximum value. Negative values of the magnetoresistive ratio cannot be explained by the usual theory of semiconductors. At the present time it also is not clear how Hung's model of impurity band conduction can account for negative values of the magnetoresistive ratio.