The Fermi surface of caesium

Abstract

A study of the de Haas-Van Alphen effect in caesium by the pulsed field method, under carefully controlled experimental conditions, has yielded information about the orientation dependence of the Fermi surface cross-section. A computer analysis of the results in terms of cubic harmonic series has indicated a probable radial distortion of some +3.3% in the [110] direction, — 0.9 % in the [100] direction, and — 1.4 % in the [111] direction; this is compared with the predictions of band structure calculations which, though indicating approximately the correct shape of Fermi surface, are appreciably in error as to the magnitude of the deviations from a sphere. The observed Fermi surface distortion is also discussed in terms of its effect on the low temperature thermoelectric power of caesium. The volume of the Fermi surface is found to be within a few tenths of 1 % of that calculated from published lattice constant data. Strong variations of signal strength with orientation were observed; these have been attributed in part to the effect of spin-splitting of the Landau levels.