Mossbauer study of hydrogenation, low temperature and magnetic field effects for amorphous Fe Co Zr alloys

The experimental results show that hydrogenation and low temperature make the hyperfine fields of the amorphous alloys Fe90-xCoxZr10 (x=0, 4, 10, 20) increase, but they have different influences on magnetic anisotropy, i.e. hydrogenation makes the plane anisotropy increase while low temperature makes it decrease. The hyperfine field distributions of all four amorphous alloys are bimodal, which means that the coexistence of ferromagnetic and antiferromagnetic states, hydrogenation and external magnetic field all make the percentage of antiferromagnetic states decrease. Hydrogenation and temperature effects become even stronger with decreasing Co content, which is also confirmed by the difference of the spin-wave excitation and the average hyperfine field as a function of hydrogenation time. The experimental results were explained with a 3DFM+FS+FSC magnetic structure model and a magnetic anisotropy model resulting from a dipole-dipole interaction.