The de Haas-van Alphen effect in dilute alloys of silver and gold

Abstract

Observations of the de Haas-van Alphen effect in dilute silver and gold-based alloys, using the pulsed-field technique, are used to study the effect of alloying on both the electronic relaxation time and the cross-sectional area of specific orbits of the Fermi surface. The results confirm Shoenberg's suggestion that the scattering of neck electrons for the AuAg system is less than the average for the Fermi surface and suggest that this is also true for the AuPt system. For some specimens, the scattering of neck electrons was found to be greater than the scattering derived from resistivity measurements; it is suggested that this may be due to scattering from lattice distortions such as dislocations. Comparison of the relaxation times for the 〈111〉 belly orbit with those derived from resistivity, indicates that for most specimens the results were consistent with isotropic scattering, but for some pure specimens there was a preponderance of small angle scattering, while for the AgCu system backward scattering seemed to predominate. Some developments in the technique of measuring cross-sectional areas of Fermi surface are described, which have been used to detect small differences in neck area between two specimens with a precision of better than 1 part in 1000. The results indicate that for AuPt and AuAg the neck area is smaller than for pure gold; the changes are of the same order as predicted by theory.