Maximum energy product of exchange-coupled Sm(FeCo)12/α-Fe nanocomposite particle.

The effects of the coating surface orientation of the α-Fe soft magnetic layer on the Sm(Fe_0.8Co_0.2)₁₂ hard magnetic phase and the volume fraction of α-Fe, V_Fe, on the maximum energy product, (BH)_max of exchange-coupled Sm(Fe_0.8Co_0.2)₁₂/α-Fe nanocomposite magnet particles were micromagnetics OOMMF package was systematically investigated. The (BH)_max of the reference model, Sm(Fe_0.8Co_0.2)₁₂ particles without Fe layer, was 630 kJ/m³. In contrast, in the nanocomposite magnet particle model with soft magnetic layers on both sides of the hard magnetic phase, (BH)_max reached a maximum value of 657 kJ/m³ at V_Fe = 12% (Fe layer thickness, t_Fe = 2 nm). In the model with α-Fe coating on the top and bottom surfaces of the hard magnetic phase, (BH)_max = 636 kJ/m³ at V_Fe = 4% (t_Fe = 2 nm). Furthermore, the coating of the soft magnetic phase on both sides of the hard phase particles reduces the magnitude of the demagnetizing field, H_d of the nanocomposite magnet particles, indicating that the side coating of the soft magnetic phase is effective in increasing (BH)_max. These findings allow for a greater degree of freedom in the design of nanocomposite magnets by adjusting not only the V_Fe volume fraction of the hard/soft phases but also their arrangement. [ABSTRACT FROM AUTHOR]