Crystal Structure and Magnetic Properties of Sm2Fe17Nδ Thin Films Deposited on Si (100) Substrates

This work focuses on the crystal structure and magnetic properties of the hard magnetic Sm2Fe17Nδ films prepared by dc magnetron sputtering and the subsequent nitriding process. The XRD, EDS, M-H and M-T data show that N enters the cell structure and the films with the single Th2Zn17 phase are obtained when the nitriding temperature varies from 300 to 400°C, thus the maximum value of the coercivity HC reaches 2561.7Oe. However, the Sm2Fe17 phase decomposes to the SmN nonmagnetic phase and the α-Fe soft magnetic phase with further increasing nitriding temperature, which corresponds to the decreasing HC. Furthermore, the easy magnetization direction (EMD) is found to locate randomly in the film plane. This texture can not give an excellent MR/MS higher than the Stoner-Wohlfarth limitation (MR/MS=0.5), which agrees well with the observed low MR/MS (0.58). It is suggested that the magnetization reversal process is dominated by the nucleation mechanism according to the initial magnetization curve and the dependence of HC on the field H.