Spin-echo measurements on dilute:Au197in iron and nickel

Spin-echo measurements on ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$ were performed on dilute alloys of Au (0.1 and 0.01 at.%) in Fe and Ni at 4.2 and 1.4 K. The magnetic hyperfine splitting frequencies ${\nu }_M=\left|\frac{g{\mu }_N{B}_{\mathrm{hf}}}{h}\right|$ extrapolated to 0 K were determined to be ${\nu }_M\left(\mathrm{Au}Fe\right)=93.207\mathrm{}\left(10\right)\mathrm{}$ MHz and ${\nu }_M\left(\mathrm{Au}Ni\right)=21.59\mathrm{}\left(3\right)\mathrm{}$ MHz. For Au(0.1 at.%) $\mathrm{Fe}$, the local-moment-induced electric quadrupole splitting could be resolved. The quadrupole splitting frequency ${\nu }_Q=\frac{e^2\mathrm{qQ}}{h}$ was found to be (-)1.50(5) MHz. With the known quadrupole moment of ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$, $Q=+0.547\mathrm{}\left(16\right)\mathrm{}$ b, the electric field gradient of $\mathrm{Au}\mathrm{Fe}$ is deduced to be (-)0.113(6) × ${10}^{17}$ ${\mathrm{V}/\mathrm{c}\mathrm{m}}^2$. With the known quadrupole splittings of ${}_{}{}^{198}{}_{}{}^{}\mathrm{Au}$ and ${}_{}{}^{199}{}_{}{}^{}\mathrm{Au}$ in Fe taken into account, the spectroscopic quadrupole moments of ${}_{}{}^{198}{}_{}{}^{}\mathrm{Au}$ and ${}_{}{}^{199}{}_{}{}^{}\mathrm{Au}$ are deduced to be $Q({}_{}{}^{198}{}_{}{}^{}\mathrm{Au};2^{-})=0.76\mathrm{}\left(4\right)\mathrm{}$ b and $Q({}_{}{}^{199}{}_{}{}^{}\mathrm{Au};{\frac{3}{2}}^{+})=0.55\mathrm{}\left(3\right)\mathrm{}$ b. The experimental hyperfine anomalies between ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$, ${}_{}{}^{198}{}_{}{}^{}\mathrm{Au}$, and ${}_{}{}^{199}{}_{}{}^{}\mathrm{Au}$ in Fe and Ni are discussed in the context of noncontact hyperfine fields.