We have subjected sputtered amorphous films of GdSingle Bond signCo alloys to a high-energy argon ion flux to study the effects of ion radiation damage on the uniaxial anisotropy of these materials. We find that a relatively low level of radiation damage ([inverted lazy s] 1014 ions/cm2) can destroy the uniaxial anisotropy if the damage is sustained in zero applied fields. A similar dosage can induce anisotropy if a strong magnetic field is applied during the ion irradiation. These experiments support the atomic-pair-ordering model of anisotropy in these materials. © 1974 American Institute of Physics.