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Why are iron-based metallic glasses magnetically soft?

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Iron-based metallic glasses are considered magnetically soft because they are easily magnetized and demagnetized by small magnetic fields. While they are mechanically hard, their magnetic softness is a result of their unique atomic structure.1

Unlike conventional crystalline magnetic materials, which contain a regular lattice of atoms, metallic glasses possess a disordered, amorphous atomic-scale structure. This lack of long-range crystalline order eliminates the magnetocrystalline anisotropy—the energy required to rotate the direction of magnetization—that is typically present in crystalline materials. By minimizing this anisotropy, the material exhibits a low coercive force and a narrow hysteresis loop, which are the defining characteristics of soft magnetic materials.123

Furthermore, the disordered structure of these glasses provides high electrical resistance. This property is highly advantageous in applications such as electrical power transformers, as it minimizes energy loss caused by unwanted eddy currents that would otherwise be induced by alternating magnetic fields.12