Magnetic properties and magnetic domains of Fe-rich Sm–Fe–Cu–Ga–C nanocomposite magnets

Nanocrystalline exchange coupled Sm2Fe14.5 divided by nCu0.5Ga2C2 magnets with enhanced remanence were produced using melt spinning. Starting from nearly single phase Sm2Fe14.5Cu0.5Ga2C2 alloys, the content of additional alpha-Fe in the composite magnets was stepwise increased up to more than 50 wt.%. A maximum remanence ratio of M-r/M-s=0.65 was found in samples containing 8.3 wt.% alpha-Fe, whereas the coercive field was mu(0)H(c)=1.6 T for this composition. Magnetic-force microscopy investigations for samples with n=0 and 3 reveal that the magnetic-domain-length scale is within the range 800-1500 nm. This is larger than the grain size, indicating the existence of exchange coupling between the hard and soft phase. (C) 1999 Elsevier Science S.A. All rights reserved.