Clusters and lattice disorder in Co0.5Al0.5-xPdx: Influence to low-temperature magnetic properties

The temperature dependence of the magnetic susceptibility in Co0.5Al0.5-xPdx when x is increased from 0.015 to 0.11 is similar to that of Co0.5Al0.5-xCox and demonstrates subsequently cluster-glass, mictomagnetic and re-entrant ferromagnetic behaviour. At the same time, its low-field and low-temperature magnetic properties are retarded with respect to the non-stoichiometric Al-Co alloy. These features are analyzed from the point of view of the remanent lattice disorder in these alloys. Specific properties of magnetic clusters in Co0.5Al0.5-xPdx such as relatively low cluster cohesive energy and rapid growth of the cluster moment when the Pd concentration is increased are used to interpret the observed magnetic field evolution of susceptibility versus temperature and the magnetic field dependence of the freezing temperature.