Magnetization andFe57hyperfine fields inY2Fe17Z3−δ(Z=H, C, or N) interstitial compounds

Abstract

Measured magnetization and ${}_{}{}^{57}{}_{}{}^{}\mathrm{Fe}$ hyperfine fields at T∼0 K for ${\mathrm{Y}}_2$ ${\mathrm{Fe}}_{17}$ and ${\mathrm{Y}}_2$ ${\mathrm{Fe}}_{17}$ ${\mathrm{Z}}_{3\mathrm{-}\mathrm{\delta }}$, with Z=H, C, or N and δ∼0.5, are analyzed to determine the influence of the interstitial atoms on the 3d magnetism. All are weak ferromagnets with a nearly-full 3d subband, although when Z=N, the magnetic moment of 38.1${\mathrm{\mu }}_{\mathit{B}}$ is very close to the fully saturated value of 39.4${\mathrm{\mu }}_{\mathit{B}}$. On a local scale, the order of hyperfine fields ${\mathit{B}}_{\mathrm{hf}}^{4\mathrm{f}}$(=35 T)>${\mathit{B}}_{\mathrm{hf}}^{6\mathrm{g}}$ (=33 T)>${\mathit{B}}_{\mathrm{hf}}^{12\mathrm{j}}$ (=30 T)>${\mathit{B}}_{\mathrm{hf}}^{12\mathrm{k}}$ (=28 T) is different from that of the local magnetic moments given by several recent band calculations for ${\mathrm{Y}}_2$ ${\mathrm{Fe}}_{17}$, ${\mathrm{\mu }}^{4\mathrm{f}}$ (=2.5${\mathrm{\mu }}_{\mathit{B}}$)>${\mathrm{\mu }}^{12\mathrm{j}}$ (=2.2${\mathrm{\mu }}_{\mathit{B}}$)>${\mathrm{\mu }}^{12\mathrm{k}}$ (=2.0${\mathrm{\mu }}_{\mathit{B}}$)>${\mathrm{\mu }}^{6\mathrm{g}}$ (=1.9 ${\mathrm{\mu }}_{\mathit{B}}$), reflecting a large 4s-transferred hyperfine field at 6g sites which have very short Fe-Fe distances. The volume of samples with Z=C and N are identical, and so the chemical effects of the interstitials can be distinguished; both the local magnetic moment and hyperfine fields are systematically smaller in the carbide than the nitride by 5% and 12%, respectively.