Heisenberg,XY, and Ising Spin-Glass Behavior in Hexagonal Metallic Systems

Dc magnetization measurements at millikelvin temperatures on dilute ZnMn, CdMn, and MgMn single crystals show that in accordance with the sign of the single-site anisotropy $D$, ZnMn is "Ising-like," i.e., the Mn moments lie parallel to the $c$ axis. CdMn is "$X-Y$-like" with the easy axis in the basal plane. MgMn is isotropic, "Heisenberg-like." Dominance of spin-orbit scattering leads to a qualitative understanding of the anisotropy.