Correlation between microstructure and first-order magnetization reversal in the SmCo5/α-Fe nanocomposite magnets

SmCo5/alpha-Fe nanocomposite magnets with different morphology have been fabricated by ball milling of the micrometer sized SmCo5 and alpha-Fe powders. The alpha-Fe grains vary from elongated nano-strips to spherical nanoparticles with increasing milling time. The inter-phase exchange coupling is enhanced with increasing milling time due to reduced grain size. The first-order reversal curves (FORCs) are taken to identify optimal conditions for exchange coupling. It has been found that the stripped morphology results in weak inter-phase exchange coupling, while enhanced exchange coupling is observed with further reduction of the soft-phase grain size. Compared with the measurement of demagnetization curves, FORC analysis provides more information on the magnetostatic as well as the exchange interactions. (C) 2011 Elsevier B.V. All rights reserved.