Structural Tuning For Enhanced Magnetic Performance By Y Substitution In Feb-Based Metallic Glasses

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 mu(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 mu(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.