Electronic structure and magnetic properties of RCo5−xMx (R=Y, Pr and M=Al, Si) system

Detailed theoretical and experimental investigations of the electronic and magnetic properties of the RCo5−xMx compounds (R=Y, Pr and M=Si, Al) have been performed. All theoretical investigations of the electronic and magnetic properties of the system have been done using the Korringa-Kohn-Rostoker (KKR) band structure method. The Si for Co substitution in RCo5 does not change the magnetic ordering: the RCo5−xSix with R=Y, Nd and Pr is ferromagnetic, whilst the heavy rare-earth containing compounds are ferrimagnetic. The important modifications induced by this substitution concerns the magnetic properties of the system: the Curie temperature and the magnetic moments of Co decrease with Si content, indicating the weakening of the Co-Co exchange interaction. The band structure calculations evidence the hybridization between the 3d electronic states of Co and the 3p states of Si as possible reason for the diminishing of Co-Co exchange interaction. Also, the volume effect on the magnetic properties of the YCo4Si was investigated using theoretical methods. The results are compared with the experimental measurements in order to distinguish the origin of magnetization reduction in YCo4Si compared with YCo4Al.