Magnetic characteristics of the ferromagnetic Fe-rich clusters in bulk amorphous Nd60Fe30Al10 alloy

Magnetic characteristics of the ferromagnetic Fe-rich clusters is the key to exploring the hard magnetism of bulk amorphous Nd-Fe-Al alloys, which has not been fully understood yet. In this work, phi 2 mm Nd60Fe30Al30 rod sample was prepared by copper mold casting method. Based on the detailed microstructure analysis, the alloy is actually composed of main amorphous phase and Hcp structured nanocrystalline Nd phase. Fe-57 Mossbauer spectrometry was employed to investigate the hyperfine structure of the alloy. Based on the refined hyperfine parameters, the distribution of the hyperfine field of the Fe-rich clusters suggests the typical amorphous structure of those clusters. The M-H loops measured at 5 K for the alloy after field cooling shifts upwards compared with that without field cooling. The reason could be attributed to the fact that parts of the clusters' moments are blocked by the strong pinning effects of antiferromagnetic coupled Nd atoms, which is difficult to be reoriented under an available applied magnetic field. The present data provides some useful information for understanding the ferromagnetic Fe-rich clusters in Nd60Fe30Al10 alloy.