Sensitive Hall Measurements on NaCl and on Photoconductive PbTe

Sensitive Hall equipment was built according to a cross-modulation method with 60-cps magnetic field, 85-cps driving current, and 25-cps selective detection. An attempt was made to measure the Hall effect of ionic conduction in sodium chloride. Theoretically its Hall mobility is expected to be of the order of ${10}^{-7\mathrm{}}$ ${\mathrm{m}}^2$/volt-sec (${10}^{-3\mathrm{}}$ ${\mathrm{cm}}^2$/volt-sec). However, excessive current noise, of the order of 10 microvolt per cps, in the sample subjected to electric and magnetic fields of the order of ${10}^4$ volt/m and 1 weber/${\mathrm{m}}^2$ at temperatures between 650°C and 800°C, prevented the observation of any Hall signal, yielding only an experimental upper limit of ${10}^{-7\mathrm{}}$ ${\mathrm{m}}^2$/volt-sec (${10}^{-3\mathrm{}}$ ${\mathrm{cm}}^2$/volt-sec) for the mobility.