A novel high entropy FeCoNi(GaCu)1.0 alloy with attractive soft magnetic properties

The new FeCoNi(GaCu)1.0 alloy has interesting soft magnetic properties at room temperature compared to other high entropy magnetic alloys (HEMAs). It is a single-phase material with high saturation magnetization Ms = 114 Am2⋅kg−1, high relative magnetic permeability 1675, and low coercive field 320 A m−1. In addition, it presents a TC = 591 °C. The spin wave stiffness is D = 85.21 meV Å2. This value is 3 times smaller than in pure Fe, thus exchange interaction among Fe, Co, and Ni atoms is smaller than those between Fe-Fe atoms, causing TC to decrease. The saturation magnetostriction λs is 5.7 × 10−6 and is as small as others λs values also found in other based FeCoNi HEMAs. Those small λs may be caused by the diffuse distortions of the lattice, a known effect on HEAs, which may be interfering in the magnetoelastic interaction between the magnetic moments and the lattice.