A hybrid coercivity mechanism for exchange-coupled nanocomposite permanent magnets

Lei Qiu¹，Li Zhao¹，Xiaojiao Weng¹，Laichuan Shen¹，Guoping Zhao^1,2,3，Fang Wang²，Linhua Xie¹

1. College of Physics and Electronic Engineering, Sichuan Normal University2. Collaborative Innovation Center for Shanxi Advanced Permanent Materials and Technology3. State Key Laboratory of Metastable Materials Science and Technology, Yanshan University

摘 要：We propose a hybrid coercivity mechanism for exchange-coupled hard/soft multilayers, which incorporates elements of both the traditional nucleation and pinning mechanisms based on both threedimensional（3 D） and one-dimensional（1 D） micromagnetic calculations. The magnetic reversal starts with the nucleation of the domain wall near the defects or soft phases, which ends by the pinning usually in the same place. Therefore, pinning near the nucleation centers are the dominant coercivity mechanism for both exchange-coupled nanocomposites and so-called single-phased permanent magnets. Our proposed coercivity mechanism and calculated results agree very well with available experimental data,especially the recently reported high energy products achieved in NdFeB and SmCo based hard/soft multilayers. The hybrid coercivity mechanism can be readily extended to single-phased permanent magnets with defects and other magnetic systems.

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