Fermi Surface of Pb under Hydrostatic Pressure

Measurements of the effect of hydrostatic pressure on the Fermi surface of lead are reported. The frequencies of the $\alpha$, $\beta$, and $\gamma$ oscillations were all found to increase by about 0.3% k${\mathrm{bar}}^{-1\mathrm{}}$, a rate more than twice that expected from scaling of the Fermi surface with volume. The pressure results on the $\beta$ oscillations provide evidence for the association of these oscillations with the $\nu$ orbit. Estimates of the variations with pressure of the Fourier coefficients of the pseudopotential are obtained, as well as estimates of the average values of the diagonal components of Pippard's deformation parameter for the three orbits. Our results suggest that simple pseudopotential-model calculations can give at best a qualitative estimate of the potential change resulting from small variations of the wave vectors with pressure.