Magnetic study of pseudo-ternary compound Y_0.6Th_0.4Co₄B under pressure

Abstract

The magnetic properties of  Y_0.6Th_0.4Co₄B 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) μ_B). 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 Y_0.6Th_0.4Co₄B 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 Y_0.6Th_0.4Co₄B intermetallic compound.

Keywords:

• Rare earth–3d transition metal compounds
• Hard magnetic material
• Pressure effect