Small-Field Galvanomagnetic Tensor of Bismuth at 4.2°K

Abstract

Values of carrier concentrations and mobilities in large monocrystalline samples of bismuth at 4.2°K have been derived from measurements of all the galvanomagnetic tensor components through second order in magnetic field. Fields of the order of one gauss and less are required, and a superconducting chopper amplifier detects the minute voltages involved. The electron concentration is found to be 2.5×${10}^{17}$ ${\mathrm{cm}}^{-3\mathrm{}}$, and the concentration of "light" holes is very nearly the same. When compared with cyclotron resonance and de Haas-van Alphen experiments, the results are consistent with a three-ellipsoid model for electrons and a single ellipsoid for "light" holes. There is no indication of the presence of "heavy" holes in a concentration comparable to the other carriers. Electron and "light"-hole relaxation times are isotropic to within a factor of 2; for electrons, $\tau ė2\times {10}^{-10\mathrm{}}$ sec, and for holes, $\tau ė5\times {10}^{-10\mathrm{}}$ sec. Some of the effects of temperature and of larger magnetic fields are discussed.