Abstract
The magnetic properties of Y0.6Th0.4Co4B are studied to characterize the magnetic behaviour of the Co sublattice. Assuming that Y or Th has no effect on magnetic properties, one can think this behaviour to remain unchanged in all RCo4B compounds, where R is a non-magnetic element. However, it has been found that YCo4B and ThCo4B have different magnetic properties. Substituting Th for Y in YCo4B induces a decrease in the Curie temperature (from 378(2) to 302(2) K) and a decrease in the saturation magnetization (from 3.0(1) to 1.5(1) μB). Both the change of chemical pressure effect (due to the change of cell volume) and the change of valence could explain this behaviour. In order to isolate the effect of pressure, we synthesized the intermediate substituted compound Y0.6Th0.4Co4B and studied the evolution of its magnetic properties under hydrostatic pressure. We found the sensitivity of the Curie temperature to be dT C/dP=−0.7(2) K/kbar. The results strongly support the dominant effect of valence electrons on the magnetic properties of the Y0.6Th0.4Co4B intermetallic compound.