The electronic structure of the novel rare-earth permanent magnet Sm2Fe17N3

Abstract

Electronic and magnetic properties of the novel rare-earth permanent magnet Sm2Fe17N3 are investigated by performing self-consistent local density-functional electronic-structure calculations. The authors also report valence-band photoemission studies on Sm2Fe17, which is the matrix compound of Sm2Fe17N3, and on Nd2Fe17 for comparison. Employing the LMTO linearized muffin-tin orbital band method, they have obtained electronic band structures for both paramagnetic and ferromagnetic phases of Sm2Fe17N3, Sm2Fe17, and Nd2Fe17. It is found that N atoms substantially reduce the magnetic moment of neighbouring Fe atoms through the hydridization interaction and play a role in stabilizing the structure. The average magnetic moment of Fe atoms in the ferromagnetic phase of Sm2Fe17N3 is estimated to be 2.29 mu B, which is approximately 6% larger than the magnetic moment of Sm2Fe17, 2.16 mu B. Photoemission spectroscopy (PES) measurements show that the bulk Nd and Sm atoms are nearly trivalent in Nd2Fe17 and Sm2Fe17, and that broad 4f PES line shapes reflect the hybridization between Nd/Sm 4f and Fe 3d states. The experimental Fe 3d PES spectra are compared with the calculated Fe 3d angular-momentum-projected local density of states (PLDOS) for Nd2Fe17 and Sm2Fe17. The measured Fe 3d PES band widths are comparable to the calculated Fe 3d PLDOS widths below EF, but the peak positions lie in between the calculated peaks of the paramagnetic and ferromagnetic Fe 3d PLDOS.