Inserting a nonmagnetic spacer layer in Nd2Fe14B/α″-(FeCo)16N2 bilayers significantly improves their coercivity
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The hysteresis loops, magnetic reversal processes, and energy variation of exchange-coupled Nd2Fe14B/α″-(FeCo)16N2 bilayers inserted with a nonmagnetic spacer layer were systematically investigated based on the object-oriented micromagnetic framework (OOMMF) software. The insertion of a nonmagnetic spacer layer can greatly improve the coercivity of the system. The coercivity of the system with different contact areas (CAs) between the Nd2Fe14B and α″-(FeCo)16N2 layers was discussed. It was calculated that the coercivity with 16% CA was about three times larger than that of soft/hard bilayers. The increased coercivity is attributed to the domain wall pinning. In addition, the effects of a deviation angle β between the easy axis and the applied field and different thicknesses of soft layer on the coercivity of the system were analyzed. The system possesses optimal magnetic properties and maximum coercivity when the applied field is applied along the easy axis. Furthermore, both nucleation fields and coercivity decrease monotonically with the increase of the soft layer thickness. Our results are useful in tuning the coercivity of the nanocomposite magnetic materials.
This work is supported by the NSFC (Nos. 51301099, 11404202 and 51571135), the Natural Science Foundation of Shanxi Province (Nos. 2013011014-4 and 2013021010-3).
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