High- and Low-Field Limits for the Hall Coefficient of Potassium

The Hall coefficient ($R$) for homogeneous potassium single crystals was measured at 4.2°K in magnetic fields ($H$) up to 85 kG. Above 15 kG, $R$ approached $H$-independent values in excellent agreement with free-electron calculations. Thus, the Fermi surface must be simply connected. Below 15 kG, $R$ exhibited weak $H$ dependence stemming almost unambiguously from scattering anisotropy (due predominantly to phonons). At low $H$, $R$ is compared with pseudopotential calculations. Correlations between $R$ and magnetoresistance are identified for either scattering or inhomogeneity phenomena.