Magnetic properties of a Fe-based amorphous alloy with stress gradient.

• Magnetic properties of a Fe-Si-B amorphous alloy with stress gradient were studied. • Magnetic anisotropy and coercivity evolve separately. • Compressive stress hinders the reversible magnetization vector rotation. • Coercivity is irrelevant to the coherent stress. The magnetic properties and domain structure of a Fe 78 Si 9 B 13 amorphous alloy with a stress gradient from upper to the lower surface were investigated. We found that the magnetic properties of the samples vary significantly upon stress variation. Specifically, the magnetic anisotropy increases linearly with the maximum stress, whereas the coercivity, although higher than the one without stress, remains reasonably small. The phase contrast in magnetic force microscopy image and the fingerprint-like domains in magneto-optical Kerr microscopy images for ribbon surface with compressive stress demonstrate the presence of perpendicular anisotropy due to the magneto-elastic coupling. As a result, the compressive stress hinders the reversible magnetization vector rotation and makes the magnetization hard to be saturated. However, the stress causes no irreversible effects, neither on the domain wall movement nor on the magnetization rotation. Thus it is irrelevant to the coercivity. These results are different from the situation of the inhomogeneously distributed quenched-in stress enlarging the coercivity in Fe-based amorphous alloys. [ABSTRACT FROM AUTHOR]