Effect of Hydrostatic Pressure and Pd Doping on the Fermi Surface of AuGa2

The effect of hydrostatic pressure on most of the reported cross-sectional areas of the Fermi surface of Au${\mathrm{Ga}}_2$ for fields along principal symmetry directions is reported. Pressure derivatives of these cross sections were obtained using the fluid-He phase-shift technique. de Haasvan Alphen frequencies were also measured for $\overrightarrow{\mathrm{H}}\parallel \mathrm{}\left[111\right]\mathrm{}$ to maximum pressures of ∼ 9 kbar generated in solid He. The results in general are found to be in good qualitative agreement with the band model of Switendick and Narath. A striking departure from linearity in the pressure dependence of the cross section associated with the arms of the third-zone hole surface occurs near 6 kbar. Also reported are some results of the effect of adding Pd to Au${\mathrm{Ga}}_2$ on these same third-zone arms which are in rough qualitative agreement with a rigid-band picture.