A first-principles approach combining density functional and dynamical mean-field theories in conjunction with a quasi-atomic approximation for the strongly localized 4f shell is applied to Nd2Fe14B-based hard magnets in order to evaluate crystal-field and exchange-field parameters at rare-earth sites and their corresponding single-ion contribution to the magnetic anisotropy. In pure Nd2Fe14B, our calculations reproduce the easy-cone to easy axis transition; theoretical magnetization curves agree quantitatively with experiment. Our study reveals that the rare-earth single-ion anisotropy in the "2-14-1" structure is strongly site-dependent, with the g rare-earth site exhibiting a larger value. In particular, we predict that increased f and g-site occupancy of R= Ce and Dy, respectively, leads to an increase of the magnetic anisotropy of the corresponding (Nd,R)2Fe14B substituted compounds.
@article{arxiv.2206.15093,
title = {Ce and Dy substitutions in Nd$_{2}$Fe$_{14}$B: site-specific magnetic anisotropy from first-principles},
author = {James Boust and Alex Aubert and Bahar Fayyazi and Konstantin P. Skokov and Yurii Skourski and Oliver Gutfleisch and Leonid V. Pourovskii},
journal= {arXiv preprint arXiv:2206.15093},
year = {2022}
}