A New Method for Precision Measurement of the Hall and Magneto-Resistive Coefficients

Abstract

A circuit capable of measuring alternating current potentials up to 1000 microvolts with a precision of 0.01 microvolt has been devised and applied to the measurement of the galvanomagnetic coefficients of semiconductors and metals. The circuit consists essentially of a peaked amplifier applied to the out-of-balance signal between an alternating current potentiometer and the potential being measured. The galvanomagnetic coefficients are so related to the potentials that the entire measurement becomes independent of the current. As an example of the results obtainable, data are given to show the variations of the Hall and magneto-resistivity coefficients during the high temperature graphitization of index rod. The precision of the final data is of the order of one-quarter percent.