The critical behavior of spin-reorientation phase transitions in the hard magnetic intermetallics (${\mathrm{Er}}_{\mathrm{x}}$${\mathrm{R}}_{1\mathrm{-}\mathrm{x}}$${)}_2$${\mathrm{Fe}}_{14}$B (R=Dy and Nd) has been studied with ac low-field susceptibility, ${\chi }_H$, and cone-angle measurements. A simple model for scaling the low-field susceptibility has been developed and applied to the present series of compounds. The critical exponents for ${\chi }_H$ have been determined for some well-behaved compounds.

• Received 15 March 1989

DOI:https://doi.org/10.1103/PhysRevB.40.7192