Magnetic properties of amorphous B‐rich R‐Fe‐B alloys

The magnetic properties of amorphous and crystallized B‐rich R‐Fe‐B alloys with R=Y, Pr, Nd, and Gd have been studied from 4.2 to 300 K using ac susceptibility and SQUID magnetometry. The amorphous samples with R=Y, Pr, and Nd show spin‐glass‐type transitions with ordering temperatures at about 150, 200, and 250 K, respectively. The magnetization of the samples is found to decrease from light to heavy rare earths to yttrium corresponding to μFe values from 1.35 to 0.74 μB. The magnetic properties can be explained by a noncollinear arrangement of the rare‐earth and Fe magnetic moments. Crystallized samples consist of multiple phases with R1.1Fe4B4 as the majority phase; for the 12% Nd sample Fe2B is believed to be one of the minority phases while for 13% Nd the minority phase is R2Fe14B.