Defect structure and magnetic moments in the β-phases of CoAl and CoGa

The atomic magnetic susceptibility χ_A of homogeneous β-phases of Co?Al and Co?Ga has been measured in the temperature range from 10 to 300°K. Below 50 at.% Co, χ_A can be described adequately by a Curie law, and for higher Co concentrations a Curie-Weiss law is obeyed. The results are interpreted in terms of a defect structure based on the antistructure cobalt concentration. This treatment is shown to be superior to previous models in that it is now possible to treat the whole range of homogeneous β-phase alloys with a single model. The relationship between the effective magneton number and the Co antistructure atom concentration is linear for both the Co?Al and Co?Ga β-phase above the stoichiometric ratio of Co.