Monthly archives: December, 2014

New paper: “Grain-size dependent demagnetizing factors in permanent magnets”

Our new paper “Grain-size dependent demagnetizing factors in permanent magnets” has been published in Journal of Applied Physics (JAP). http://dx.doi.org/10.1063/1.4904854

UPDATED UPDATE: an updated reprint version that should be better for Google Scholar crawling is now available here

 

Abstract: The coercive field of permanent magnets decreases with increasing grain size. The grain size dependence of coercivity is explained by a size dependent demagnetizing factor. In Dy free NdFeB magnets, the size dependent demagnetizing factor ranges from 0.2 for a grain size of 55 nm to 1.22 for a grain size of 8300 nm. The comparison of experimental data with micromagnetic simulations suggests that the grain size dependence of the coercive field in hard magnets is due to the non-uniform magnetostatic field in polyhedral grains.

The article is free to download for 30 days, after which it will be available to journal subscribers. At that time I will post a reprint version on this site, which will be indexed by Google Scholar and other search engines.

Grain size paper: Fig. 5 Demagnetizing field of a uniformly magnetized cube evaluated at a distance of d =1.2Lex from the edge. Solid line: Component perpendicular to the easy axis. Dashed line: Component parallel to the easy axis.

Grain size paper: Fig. 5 Demagnetizing field of a uniformly magnetized cube evaluated at a
distance of d =1.2Lex from the edge. Solid line: Component perpendicular
to the easy axis. Dashed line: Component parallel to the easy axis.




Paper “Hard Magnet Coercivity” published in proceedings of REPM2014

This August Prof. Dominique Givord of Institut Néel – CNRS presented our paper titled “Hard Magnet Coercivity” during the 23rd International Workshop on Rare earth and Future Permanent Magnets and Their Applications (REPM2014) in Annapolis, Maryland.

The manuscript was included in the conference proceedings and we would now like to make the reprint available to the wider public: Please click here for the PDF file.

Abstract: Based on a critical analysis of the experimental coercive properties, general considerations on the reversal mechanisms in RFeB magnets are recalled. By plotting together the experimental parameters obtained in various magnets, common features of the reversal processes are demonstrated. Modeling provides an almost quantitative description of coercivity in these materials and permits connecting the defect characteristic properties to reversal mechanisms.

 

Annapolis, Image in Public Domain

Annapolis, Image in Public Domain