We study the local magnetic anisotropy due to Nd ions located around surfaces of Nd2Fe14B within the crystal field theory based on first-principles calculations. The Nd ions on the (001) surface exhibit A20 < 0, that is, the in-plane anisotropy, as reported previously, but those on the (100) surface exhibit A20 > 0, which is consistent with the bulk c-axis uniaxial anisotropy. The physical origin of these conflicting local anisotropies can be understood from the 6p and 5d valence charge distributions realized in the Nd2Fe14B structure.
- and compounds
- permanent magnets