SURFACE REFLECTION AND NONLINEARITIES IN AC HALL MEASUREMENTS OF LIQUID-METALS

It has been confirmed that nonlinearities at the electrode interface c ause spurious signals similar to Hall signals when the two-frequency a c method is applied to Hall measurement of liquid state materials. Fro m the analysis of the results of surface reflection of a laser beam, H all coefficients for liquid mercury and gallium have been obtained in the higher frequency region using our recently developed ac-dc method. It has also been found that other spurious signals result from the el ectric resistance change caused by sample movements and intrinsic magn etoresistance due to a Lorentz force. The resistance change in the hig her frequency region is proportional to B and B-2 in the liquid states , however no change is observed in the solid state.