Magnetic Behavior of Soft Magnetic FeMoCuB Metallic Glass at Low Temperature

We have studied a NANOPERM-type Fe₇₆Mo₈Cu₁B₁₅ metallic glass with emphasis upon its magnetic properties at low temperatures. Temperature evolution of magnetization measured under zero-field cooling and field cooling conditions upon samples with different amounts of nanocrystalline grains have unveiled a two-phase behavior in temperature range from 50 up to about 200 K. In order to understand the correlation between the structural arrangement and resulting magnetic properties, we have employed a local probe method of ⁵⁷Fe Mössbauer spectrometry performed at 300 and 4.2 K. The latter experiments were also accomplished in an external magnetic field of 6 T. Magnetically distinct regions were unveiled in the amorphous structure of the as-quenched and annealed samples. They are demonstrated by the distributions of hyperfine magnetic fields.