Self-hall-effect measurements in bismuth with repetitive magnetic-field pulses

Abstract

Using the technique of capacitor discharge, a repetitive pulsed magnetic field has been obtained with the following characteristics: 67 kOe field intensity in a coil of about 1 cm3 volume at a repetition rate of 50 Hz; the pulse length is about 10 μs, practically sinusoidal in shape. Using sampling- and phase-sensitive detection an improvement in the signal-to-noise ratio of about 103 in respect to the single-shot technique can be achieved. The repetitive pulsed magnetic field has been used to investigate transport properties of polycristalline Bi with the self-Hall effect. For electron and hole mobilities we have obtained 2.3 and 18.7 for electrons, 1.47 and 7.2 m2/V·s for holes at 273 and 80 °K respectively. Moreover the nonintrinsic behavior of Bi at both temperatures has been proved to be not due to the presence of impurities, but to thermal excitation of electrons living behind holes which do not partecipate in the conduction. This is in accord with the possibility of existence of open surfaces as suggested by Lifshitzet al. By definingx=(n2−n1)/n1 as a measure of the nonintrinsic behavior, we have obtainedx=−0.096 andx=−4.1·10−3 at 273° and 80 °K respectively.