Conduction electron-local moment interactions in metals via dHvA waveshape analysis

Abstract

Detailed information about conduction electron-magnetic impurity interactions is contained in the harmonic content of the de Haas–van Alphen (dHvA) effect. Using the first three harmonics of the dHvA effect, the spin-up and spin-down conduction electron scattering rates, Xσ= (h//2πkB) 〈τ−1〉σ, may be separately determined, along with the magnitude of the conduction electron-local moment exchange energy shift, ΔEex=μBHex. Quantum oscillations arise from extremal orbits on the Fermi surface, so that the measured quantities are orbital averages, and one has available a spin-resolved, k-space spectrometer. Results obtained by applying dHvA waveshape analysis techniques to carry out a survey of conduction electron interactions with both d-shell (Cr, Fe, Co) and f-shell (Gd, Ho, Yb) moments in Au include: (1) The observation of strongly spin-dependent scattering (X↑≠ X↓) by d-shell impurities, in contrast to spin-independent scattering by f-shell impurities; (2) exchange energy shifts of both ferro- and antiferromagnetic sign for f-shell impurities, and about an order of magnitude smaller than the purely antiferromagnetic exchange observed for d-shell impurities; (3) observation of impurity-impurity interaction effects in Au (Co) at impurity concentrations ≲500 at. ppm; (4) evidence from partial wave analysis that the local moment-conduction electron interaction proceeds almost entirely via the d-wave part of the conduction electron wavefunctions.