The Hall Effect in a Bismuth Crystal

The Hall effect has been measured in plates cut in different directions from a single large crystal of bismuth. At room temperatures when the field H is perpendicular to the trigonal axis, a negative Hall coefficient R is obtained, decreasing from about 15 for $H=1000$ gauss to about 7 for $H=8000$. For H parallel to the trigonal axis a positive coefficient of about unity is obtained, increasing slightly with the field. At -186^∘{}C R is positive for all orientations of the axis and decreases as H increases. The maximum R observed at -186^∘{}C was + 15 at $H=600$. A plate made of compressed bismuth powder gave $R=+7$, approximately, at -186^∘{}C. Beckman found large negative values of R for similar plates at this temperature. The Hall e.m.f. cannot be resolved into positive and negative components at -186^∘{}C in the way suggested by Becquerel.