Magnetisation dynamics of as quenched and pulse annealed soft metallic glasses

Abstract

Pulse annealing method (PAM) is a practical and effective method to improve the magnetic characteristics of metallic glasses. Pulse annealing method overcomes oxidation problems during the annealing process. It minimises the difficulties in managing the crystallisation steps and causes low coercivity in contrast to high susceptibility in milliseconds. In this work, Fe₇₇Cr₂Si₅B₁₆ and Fe₃₉Ni₃₉Mo₄Si₆B₁₂ metallic glasses were annealed by PAM. The ferromagnetic resonance spectra were measured, and the angular variation of resonance fields at the out of plane geometries was studied. The effective magnetisation and g factor fitting parameters were obtained as 3450 and 3750 Oe for Fe₇₇Cr₂Si₅B₁₆ and Fe₃₉Ni₃₉Mo₄Si₆B₁₂ respectively from the angular variation of the resonance field. The M–H loops at room temperature were also plotted, and the changes of the magnetic properties were observed after pulse annealing. Amorphous to nanostructure steps can be seen from this method without any doubt.

Keywords:

• Metallic glass
• Fe₇₇Cr₂Si₅B₁₆
• Fe₃₉Ni₃₉Mo₄Si₆B₁₂
• Pulse annealing
• Ferromagnetic resonance
• Effective magnetisation
• g factor
• M–H loop

The authors are grateful to Professor M. R. J. Gibbs from the University of Sheffield Engineering Material Department for his support and valuable suggestions.