Measurement of Conduction-Electron Spin-Density Oscillations in OrderedFeSi Alloys

Pulsed NMR hyperfine field measurements have been made on ordered ${\mathrm{Fe}}_{1-x}{\mathrm{Si}}_x$ alloys for $0.181\le x\le 0.249$. Using ordered compounds greatly improves the accuracy with which internal-field shifts due to the first nine neighbor shells can be measured. A number of effects which were difficult to observe in dilute alloys are easily measurable. Dipolar structure and saturation or shielding effects are seen for various neighbor shells. We see no damping of the spin density oscillations with alloying. This allows the determination of a lower limit for the mean free path of the conduction electrons in the alloys. The third-, fourth-, and sixth-nearest-neighbor Fe atoms give positive polarizations. The measured hyperfine field shifts are extrapolated and combined with dilute alloy data to obtain the spin-density oscillations surrounding an Fe atom in pure Fe.