High magnetic moment in Fe87B11Au2 ribbons

Amorphous Fe87B11Au2 ribbons that are stable above 300 K displayed saturation magnetization Ms of 223 emu/g at 4.2 K. The deduced average Fe atomic moment μFe was 2.46 μB, which is relatively high compared to μFe=2.13 μB in Fe87B13. The higher Fe moment is attributed to a quenched‐in, high‐volume Fe lattice (similar to that found in amorphous Fe‐Au films) stabilized by Au and B atoms. Upon annealing, three crystallization stages were observed. First, a α‐Fe phase with about 3 at.% Au emerged at around 620 K followed by a Fe2B phase at ≊745 K. At ≊790 K, a Au‐rich phase emerged. There were decreases in Ms (4.2 K) as the isothermal annealing temperature was increased, with the largest decrease coinciding with the precipitation of Fe2B.