Magnetic properties of Ho1−xMmxCo2 (x=0, 0.1, 0.2, 0.3 and 0.4) alloys and their hydrides

The influence of Mm (Mm=mischmetal) substitution and hydrogen absorption on the magnetic properties of Ho1−xMmxCo2 (x=0, 0.1, 0.2, 0.3 and 0.4) alloys have been determined through the temperature dependence of ac susceptibility and thermopower measurements. The changes in magnetic-ordering temperature of Ho1−xMmxCo2 alloys have been explained based on the dilution of the magnetic ions and weakening of 4f–3d exchange interactions. The gradual disappearance of the magnetic transition temperature upon increasing hydrogen concentration (y) has been interpreted by the lattice expansion and charge transfer between absorbed hydrogen and 3d-band of Ho1−xMmxCo2.