Influence of defect thickness on the angular dependence of coercivity in rare-earth permanent magnets
Bance, S; Oezelt, H; Schrefl, T; et al.Ciuta, G; Dempsey, NM; Givord, D; Winklhofer, M; Hrkac, G; Zimanyi, G; Gutfleisch, O; Woodcock, TG; Shoji, T; Yano, M; Kato, A; Manabe, A
Date: 9 May 2014
Article
Journal
Applied Physics Letters
Publisher
American Institute of Physics (AIP)
Publisher DOI
Abstract
The coercive field and angular dependence of the coercive field of single-grain Nd$_{2}$Fe$_{14}$B permanent magnets are computed using finite element micromagnetics. It is shown that the thickness of surface defects plays a critical role in determining the reversal process. For small defect thicknesses reversal is heavily driven by ...
The coercive field and angular dependence of the coercive field of single-grain Nd$_{2}$Fe$_{14}$B permanent magnets are computed using finite element micromagnetics. It is shown that the thickness of surface defects plays a critical role in determining the reversal process. For small defect thicknesses reversal is heavily driven by nucleation, whereas with increasing defect thickness domain wall de-pinning becomes more important. This change results in an observable shift between two well-known behavioral models. A similar trend is observed in experimental measurements of bulk samples, where a Nd-Cu infiltration process has been used to enhance coercivity by modifying the grain boundaries. When account is taken of the imperfect grain alignment of real magnets, the single-grain computed results appears to closely match experimental behaviour.
Physics and Astronomy
Faculty of Environment, Science and Economy
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