Fermi Surface of Thallium: Radio-Frequency Size Effect

Abstract

Radio-frequency size-effect measurements were made on high-purity single-crystal thallium plates approximately 0.1-0.25 mm thick. Extremal calipers of the Fermi surface obtained from the data were self-consistently fitted with a Fermi-surface model consisting of a third-band hole surface and fourth- and fifth-band electron surfaces. The Fermi-surface model developed from the data is appreciably different from either the free-electron model or the model arising from a previous energy-band calculation. In particular, no calipers were observed that could be assigned to pockets of third-band holes at the $M$ point in the Brillouin zone. The fourth-band electron hexagonal network is found to be considerably distorted from the free-electron model, with no connection along the $\ensuremath{\Gamma}A$ direction and no pockets in the $\ensuremath{\Gamma}\mathrm{MK}$ plane. Comparisons between the present model and recent de Haas-van Alphen measurements are made.