Combinatorial Sputtering Synthesis of Tbcu7-Type Sm-Fe Based Compounds: A Study on Phase, Composition, and Extrinsic Magnetic Properties

Abstract

TbCu7-type SmFex (x=6.4 to 12.7) and SmFexN (x=6.8 to 12.8) composition spread thin films were fabricated using a combinatorial sputtering system to study the effect of composition  on the phase formation and extrinsic magnetic properties. A high-throughput phase and composition analysis was carried out using x-ray diffraction and x-ray fluorescence measurements respectively, at different Fe:Sm ratio positions on the thin film. The Fe:Sm ratio significantly affects the formation of main TbCu7-type phase and the secondary ferromagnetic α-Fe phase. The optimal Fe:Sm ratio, which exhibits the highest fraction of the TbCu7-type phase free from α-Fe, was identified as SmFe9.8 and SmFe9.5N. The coercive field (μ0Hc) was estimated using a position-dependent polar-magneto-optical Kerr effect hysteresis loops and was found to range from 1.1 T (for SmFe6.8N) to 0.06 T (SmFe12.8N). The remanent magnetization (μ0Mr) values estimated using a superconducting quantum interference device-vibrating sample magnetometer measurements (on cut samples) ranges from 0.8 T to 1.2 T for the α-Fe-free compositions. The optimal composition, SmFe9.5N, exhibits a µ0Hc of ~0.8 T and a µ0Mr of ~1.2 T. Furthermore, microstructural characterization was carried out on the SmFe9.5N using scanning transmission electron microscopy to correlate with its phase and magnetic properties. Overall, this study demonstrates the effect of composition variation on the phase and extrinsic magnetic properties of this compound, facilitating the selection of desired compositions with targeted magnetic properties.

Keywords: Combinatorial sputtering, high-throughput characterization, Sm-Fe-based thin films, permanent magnetic materials