The Longitudinal Thermomagnetic Potential Difference in a Bismuth Crystal

Abstract

The longitudinal thermomagnetic potential difference in a bismuth crystal has been measured at room temperature for various orientations of heat current, magnetic field, and crystal axis. The results are plotted to show the change of thermoelectromotive force as a function of magnetic field strength. When the heat current is parallel to the crystal axis the field produces an apparent increase of thermoelectromotive force, the maximum being about 7 percent in a field of 7000 gauss. When the heat current is perpendicular to the crystal axis the field produces a decrease of thermoelectromotive force, the maximum being 23 percent in a field of 7000. Some of the data are in poor agreement with previous work by Lownds and Defregger. The results may be explained qualitatively by assuming that a magnetic field produces a structural change of some sort in the atomic system of bismuth. This change, in the direction normal to the field, is essentially different from the change parallel to the field.