The magnetic moment reversal at each of the two inequivalent Nd sites in a single crystal of ferromagnetic ${\mathrm{Nd}}_2{\mathrm{Fe}}_{14}\mathrm{B}$ is probed by dichroic resonant diffraction of circularly polarized x rays. The results, supported by theory, show that the $c$-axis intrinsic magnetic stability of this superior permanent magnetic material arises predominately at one of the Nd sites ($g$). The other site ($f$) undermines magnetic stability by favoring a magnetic moment orientation in the basal plane.

• Received 1 August 2005

DOI:https://doi.org/10.1103/PhysRevLett.95.217207