Nuclear magnetic resonance on oriented nuclei was carried out using a sample of dilute ${}^{91}\mathrm{Y}$ and ${}^{91m}\mathrm{Y}$ in iron prepared by ion implantation of radioactive precursor Rb isotopes. For ${}^{91}\mathrm{Y}\mathrm{Fe}$, the beta-ray asymmetry was utilized to measure the magnetic hyperfine interaction frequency, ${\nu }_0=73.566\left(22\right)\mathrm{MHz}$, which led to the magnetic hyperfine field, $B_{\mathrm{HF}}=-29.4\left(2\right)\mathrm{T}$, by using the known nuclear $g$-factor. The field shift of the resonant frequency, $d{\nu }_0∕d{B}_0=-2.501\left(17\right)\mathrm{MHz}∕\mathrm{T}$ for ${}^{91}\mathrm{Y}\mathrm{Fe}$, implies a Knight shift value, $K=0.0\left(8\right)\%$. The interaction frequency and the field shift of ${}^{91m}\mathrm{Y}\mathrm{Fe}$ obtained via the gamma-ray detection confirmed the previously reported results. A ratio of the measured ${\nu }_0$ and $d{\nu }_0∕d{B}_0$ values for both ${}^{91}\mathrm{Y}\mathrm{Fe}$ and ${}^{91m}\mathrm{Y}\mathrm{Fe}$ gave rise to the hyperfine anomaly, ${}^{91}\Delta ^{91m}=-4.2\left(8\right)\%$, which can explain discrepancies in the $B_{\mathrm{HF}}$ values of YFe as determined by various experiments.

• Received 18 April 2004

DOI:https://doi.org/10.1103/PhysRevB.70.132405