Effect of nitrogenation and hydrogenation on the magnetic properties and structure of the Sm$_2$Fe$_{17}$ alloy: analysis of XMCD data

Changes in the local magnetic and structural properties of Sm$_2$Fe$_{17}$ alloys at nitrogenation and hydrogenation of samples have been studied by the X-ray magnetic circular dichroism (XMCD) technique at the Fe $K$ absorption edge and Sm $L_3$ absorption edge using synchrotron radiation. The results have been discussed in comparison with X-ray diffraction data and macroscopic vibration magnetometry measurements. The observed changes in XMCD spectra indicate a noticeable effect of nitrogenation on the local magnetic properties of sublattices of both iron and samarium, whereas hydrogenation of samples makes a small effect. The mentioned effects have been analyzed and discussed in terms of the effect of nitrogen (N) and hydrogen (H) interstitial atoms on Sm $5d$ and Fe $4p$ electronic states. The effect of nitrogenation is larger than the effect of hydrogenation because the volume expansion of the crystal lattice of initial Sm$_2$Fe$_{17}$ in the case of nitrogenation is larger than that in the case of hydrogenation. The studied local magnetization curves for samarium and iron sublattices in magnetic fields up to $17$ T also indicate a strong increase in the magnetocrystalline anisotropy at nitrogenation.