Cyclotron Resonance in Sodium and Potassium

Abstract

Azbel'-Kaner cyclotron resonance has been observed in oriented single crystals of sodium and potassium. The data are isotropic in both metals and yield for the ratio of cyclotron effective mass to free electron mass the values 1.24±0.02 and 1.21±0.02 for sodium and potassium, respectively. The isotropy of the data for potassium indicates that its Fermi surface is very nearly spherical with the anisotropy in $k_F$ probably less than 1%. The interpretation of the data for sodium is complicated by the existence of a low-temperature phase transformation.