The thermal and electrical resistance of bismuth single crystals. The effects of temperature and magnetic fields

Abstract

The anomalous physical properties of bismuth, particularly as regards the reduction of the thermal and electrical conductivities in magnetic fields, have claimed the attention of a number of workers in the past. Most of the published data refers to the electrical conductivity, owing, no doubt, to the greater ease of measurement; and but little reliable work appears to have been done on the thermal conductivity, at any rate in the case of single crystals. Lounds (1902) carried out thermal-conductivity measurements employing magnetic fields up to about 5000 gauss, but the accuracy of his results was prescribed by the limitations of the method and the smallness of his crystals. Kapitza (1928) undertook an extensive investigation on the electrical conductivity of single crystals using very intense momentary fields. Banta (1932) published thermal-conductivity values using fields up to 8000 gauss, while more recently de Haas and Capel (1934) have made thermal measurements, in the absence of a field, at liquid-air and liquid-hydrogen temperatures. The results of a preliminary investigation (Kaye and Higgins 1929a) at the National Physical Laboratory on the change in thermal conductivity of bismuth single crystals in transverse magnetic fields were published in 1929. In this work, specimens, which were cut in the form of disks 25 mm. in diameter and 2 mm. thick from a large crystal grown by Bridgman’s method (1925), were tested in a “plate” type of apparatus, field strengths up to 11,000 gauss being employed in a 38 mm. air gap.