Enhancement of Maximum Energy Product by $\alpha$-Fe Coating on the Side of Rectangular Sm(Fe0.8Co0.2)12 Nanoparticles

The demagnetization process of exchange-coupled Sm(Fe
0.8
Co
0.2
)
12
/
$\alpha$
-Fe nanocomposite magnet particles with a-Fe phase coated on the sides of rectangular Sm(Fe
0.8
Co
0.2
)
12
nanoparticles and the effect of Fe phase arrangement on their
$(BH)_{\max}$
are systematically investigated from micromagnetics calculations. The
$(BH)_{\max}$
of the reference model Sm(Fe
0.8
Co
0.2
)
12
particles without Fe layer was 630 kJ/m
³
. On the other hand, the
$(BH)_{\max}$
of the nanocomposite magnet particle model, in which the four sides of the hard phase are coated with a soft phase, was found to have the highest
$(BH)_{\max}$
of 678 kJ/m
³
. This result may provide a guideline for designing high-performance magnet particle materials while reducing the use of rare metals.