THE MAGNETIC PHASES OF PSEUDOBINARY CE(FE1-XALX)2, CE(FE1-XCOX)2, CE(FE1-XRUX)2 INTERMETALLIC COMPOUNDS

Powder neutron diffraction measurements of the magnetic and structural properties of a range of pseudobinary Ce(Fe1-xMx) 2 intermetallic compounds, with M=Al, Co, Ru, are reported. In each of these pseudobinaries addition of a small amount of the metallic impurity (M) to CeFe2 reduces the ferromagnetic ordering temperature and enhances the small antiferromagnetic component which appears at low temperature. At higher impurity concentrations antiferromagnetism is achieved. This antiferromagnetism is accompanied by a cubic to rhombohedral distortion of the crystalline lattice. The antiferromagnetic component of the ordered moment in these compounds is oriented at approximately=18.5 degrees to the antiferromagnetic propagation vector ( tau =(111)). An ordered cerium moment is seen in the ferromagnetic phase of CeFe2 and Ce(Fe 1-xRux)2. This moment is coupled ferrimagnetically to the iron-sublattice moment and mu Ce/ mu Fe approximately=-0.3.