Structural tuning for enhanced magnetic performance by Y substitution in FeB-based metallic glasses

Abstract

Abstract Despite the compositional analogue to Fe71B17(NbYZr)12 metallic glass, the Fe71B17Y12 metallic glass has a saturated magnetization of Ca 108 emu g−1, more than 5 times of that in Fe71B17(NbYZr)12 (20 emu g−1). The structural origin for such significant difference in magnetic performance was investigated by x-ray absorption fine structure spectra and ab initio molecular dynamics (AIMD) simulations including simulated pair-correlation function (PCF) and Voronoi tessellation. Based on the Heisenberg model of magnetism, the narrow distribution of Fe–Fe bonds with larger distances accounts for a large Fe moment of 2.0 μ B in Fe71B17Y12, while the broad distribution of Fe–Fe bonds leads to ferrimagnetic couplings which result in the small net Fe moment of 0.45 μ B in Fe71B17(NbYZr)12. This work emphasizes how the substitution of analogous 4d transition metals induces a significantly different magnetism, which sheds lights on the development of new magnetic metallic glasses with both a promising magnetic performance and larger glass forming ability.